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April 18, 2014

Homework Help: Math: Trigonometry

Recent Homework Questions About Trigonometry

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trig
cos4x = 2cos^2(2x)-1 = 2(2cos^2(x)-1)^2 - 1 just expand that sin(x/4) = sqrt((1-cos(x/2))/2) = sqrt((1-sqrt((1-cos(x))/2)/2
Tuesday, May 29, 2012 at 3:56am

trig
1) Use double-angle identities to write the following expression, using trigonometric functions of x instead of 4x. cos 4x 2) Use half-angle identities to write the following expression, using trigonometric functions of x instead of x/4. sin x/4
Monday, May 28, 2012 at 11:36pm

trig
We form a rt. triangle: X = 6 meters = Hor. Y = Ver. = Dist. from gnd to junction of wire and pole. Z = Hyp. = Length of the wire. A = Angle bet. gnd and wire. B = Angle bet. pole and wire. A + B = 90 Deg. A = 3B. 3B + B = 90 B = 22.5 Deg. A = 3B = 3*22.5 = 67.5 Deg. Z*cosA = ...
Monday, May 28, 2012 at 8:03pm

trig
4 divided by 6 = 1.5 1.5 times 18 = 27 the answer is : 27
Sunday, May 27, 2012 at 11:20pm

trig
AB = 8 cm, AC = 6 cm, AD = 7 cm, CD = 2.82 and CAB=50° (a) the length BC (b) The size of angle ABC; (c) The size of angle CAD (d) The area of triangle ACD
Sunday, May 27, 2012 at 5:08pm

trig
An electric pole is supported to stand vertically on a level ground by a tight wire. The wire is pegged at a distance of 6 meters from the foot of the pole. The angle that the wire makes the ground is three times the angle it makes with the pole.
Sunday, May 27, 2012 at 4:35pm

trig
plot of land ABCD such that AB = 85m, BC = 75m, CD = 60m, DA = 50m and angle ACB = . Determine the area of the plot in hectares correct to two decimal places
Sunday, May 27, 2012 at 4:33pm

algebra 2/trig
x+5 1 ------- - 1= ------- x^2-2x x^2-2x
Sunday, May 27, 2012 at 1:23pm

Trig
i dot geht thhis werlk? cahn sumwone elp meh?
Saturday, May 26, 2012 at 2:52pm

Trig Help Please!!!
HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!​!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!​!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!​!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!​!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Saturday, May 26, 2012 at 2:50pm

Calc- Trig Substitution
hmm. upon rereading your answer, you are in fact correct.!!
Friday, May 25, 2012 at 5:19am

Calc- Trig Substitution
not even close :-( let x = 8secu dx = 8secu*tanu du x^2-64 = 64sec^2 u - 64 = 64tan^2 u dx/√(x^2-64) = 8*secu*tanu/8tanu = secu since ∫secu = ln|secu+tanu|, we have Recall that x = 8secu, so secu = x/8 tanu = √(x^2/64 - 1) = 1/8 √(x^2-64) ∫secu = ...
Friday, May 25, 2012 at 5:18am

Calc- Trig Substitution
integral of dx/square root(x^2-64) My answer is: ln (x/8 + square root(x^2-64)/8) +c is this right?
Friday, May 25, 2012 at 2:23am

trig
Using sin^2 x = 1-cos^2(x) the equation becomes: cos²(x)+cos(x)-2=0 Use the substitution c=cos(x) to transform the equation to : c²+c-2=0 (c+2)(c-1)=0 c=-2 or c=+1 Since cos(x) cannot equal -2, solution is rejected. Now solve for all values of 0≤x≤2π where ...
Thursday, May 24, 2012 at 8:07am

trig-math
A stairway must be built to a deck that is 20 feet above ground level. To the nearest half foot, how far from the base of the deck, on ground level, should the beginning of the stairway be placed so that the stairway forms a 60° angle from the ground?
Thursday, May 24, 2012 at 6:13am

Trig
yes. sorry. I forgot the comma
Wednesday, May 23, 2012 at 11:37pm

trig
Solve cos x-1 = sin^2 x Find all solutions on the interval [0,2pi) a. x=pi, x=pi/2, x= 2pi/3 b. x=3pi/7, x=pi/2, x=2pi/3 c. x=3pi/7, x=3pi/2, x=3pi/2 d. x=pi, x=pi/2, x=3pi/2
Wednesday, May 23, 2012 at 11:12pm

trig
let x = height of tree tan(angle) = x/27 tan(26) = x/27 x = 0.488*27 x = 13.17 = 13 m
Wednesday, May 23, 2012 at 10:56pm

trig :)
You're welcome!
Wednesday, May 23, 2012 at 10:29pm

trig
thank you so much, it helps! :)
Wednesday, May 23, 2012 at 10:17pm

trig
tan(x) has a period of π, so tan(x)=tan(x+π), in fact, tan(x+kπ)=tan(x), where k∈Z So to evaluate tan(257π/4) =tan((257/4)π) =tan(64π + π/4) =tan(π/4) I will let you figure out which answer to choose.
Wednesday, May 23, 2012 at 10:11pm

trig
evaluate the expression tan (257pi/4) a.-1 b. -(sqrt2)/2 c. 1 d. (sqrt2)/2
Wednesday, May 23, 2012 at 9:44pm

trig
A tree casts a shadow of 27 meters when the angle of elevation of the sun is 26 degrees. Find the height of the tree to the nearest meter. a. 24 m b. 15 m c. 320 m d. 13 m
Wednesday, May 23, 2012 at 9:40pm

trig
s = rθ 1.1 = 3θ θ = .366666 radians = 21°
Wednesday, May 23, 2012 at 11:52am

trig
a voltmeter's pointer is 3 cm in length. find the degrees through which is rotates when it moves 1.1 cm on the scale?
Wednesday, May 23, 2012 at 11:11am

Trig
look at the solution I gave here to a similar problem http://www.jiskha.com/display.cgi?id=126​7493976
Wednesday, May 23, 2012 at 5:01am

Trig
??? Is that a polar coordinate point? is there a missing comma? did you mean (-2 , π/6) ?
Wednesday, May 23, 2012 at 4:58am

trig
cos 2x + √2/2 =0 cos 2x = -√2/2 I know cos π/4 = √2/2 or cos 45° = +√2/2 but 2x could be in II or III 2x = π-π/4 or 2x = π + π/4 2x = 3π/4 or 2x = 5π/4 x = 3π/8 or x = 5π/8 ---> 67.5° or 112.5°...
Wednesday, May 23, 2012 at 4:56am

trig
b) to multiply two complex numbers in complex form if u = r1(cos Ø1 + isinØ1) and v = r2(cosØ2 + isinØ2) then uv = r1r2(cos(Ø1+Ø2) + isin(Ø1+Ø2) and u/v = r1/r2 (cos(Ø1-Ø2) + isin(Ø1-Ø2) so (z...
Wednesday, May 23, 2012 at 4:31am

trig
7. z = -5√3/2 + 5/2i = 5(-√3/2 + (1/2)i ) argument : tan Ø = (1/2) / (-√3/2), where Ø is in II tan Ø = -1/√3 Ø = 150° or 5π/6 radians z = 5(cos 150° + isin 150°) or 5(cos 5π/6 + isin 5π/6) in the ...
Wednesday, May 23, 2012 at 4:23am

trig
6. I will do E, you try the others the same way let z = -5 + 5i modulus z = |z| = √((-5)^2 + 5^2) = √50 = 5√2 argument: tanØ = 5/-5 = -1, where Ø is in quad II Ø = 135° G. is done the same way for D, think of it as -5 + 0i
Wednesday, May 23, 2012 at 4:11am

trig
6. Compute the modulus and argument of each complex number. I did a-c and f. D. -5 E. -5+5i G. -3-4i 7. Let z= -5sqrt3/2+5/2i and w= 1+sqrt3i a. convert z and w to polar form b. calculate zw using De Moivres Theorem c. calculate (z/w) using De M's theorem Please help with ...
Wednesday, May 23, 2012 at 12:41am

trig
Find all solutions of cos 2x + √2/2 =0. a) + or - 3/8pi +Kpi b) 2/3pi + Kpi, 5/3pi + Kpi c) + or - 2/5 +Kpi d) 2/3 pi + 2Kpi, 5/3pi + 2Kpi I really need help on this question :(
Tuesday, May 22, 2012 at 11:27pm

Trig
what are the rectangular coordinates of (-2(pi/6))? please help.
Tuesday, May 22, 2012 at 11:25pm

math trig
ln(2x-5) = 4 we raise both sides by e: e^(ln(2x-5)) = e^4 the e and ln will be cancelled, leaving only the 2x - 5: 2x - 5 = e^4 2x = e^4 + 5 x = (e^4 + 5)/2 hope this helps~ :)
Monday, May 21, 2012 at 10:55pm

math trig
ln(2x-5)= 4 how do i this problem? thanks!
Monday, May 21, 2012 at 10:45pm

TRIG
I need to state the period and 2 consecutive asymptotes on the graph for the following questions. 1: y = -3 tan pi*x period: pi (?) asymptotes: ? 2: y = 2 sec 4x period: ? asymptotes: ? 3: y = csc (x/3) period: ? asymptotes: ? 4: y = 3 cot (pi*x/2) period: ? asymptotes: ?
Monday, May 21, 2012 at 6:03pm

geometry
did you make a sketch?? This is just right-angled triangle trig tan 29.78° = h/980 h = 980tan29.78° =appr 561 feet so when the height is 280.5 feet tan Ø = 280.5/980 =.28612.. Ø = 15.97°
Monday, May 21, 2012 at 8:05am

graphing trig functions
I see the equation of a straight line, not a trig function
Monday, May 21, 2012 at 7:53am

trig
4 cos theta - 1
Sunday, May 20, 2012 at 11:31pm

graphing trig functions
given y=(3x+2pi) how would i graph one period this without a calculator? amplitude:1 period: 2pi/b = 2pi/3 is this correct? what is the minimum and maximum points?
Sunday, May 20, 2012 at 10:15pm

trig
how can you find points of a tri equation at orgin 1/4, 1/2, 3/4, and end of the period
Sunday, May 20, 2012 at 9:53pm

Trig
sin θ= sqrrt3/2 This is just your standard pi/3. So, pi/3 and 2pi/3 b. 4pi/3, 5pi/3
Saturday, May 19, 2012 at 11:10pm

Trig
Find two values of theta that satisfy the equation. give your answers in degrees (0degrees <theta<360degrees ) and radians (0<theta<2pi) a. sin θ= sqrrt3/2 b.sin θ= - sqrrt3/2
Saturday, May 19, 2012 at 10:44pm

Trig
s = rθ θ = s/r = 10/16 = 5/8
Friday, May 18, 2012 at 2:09pm

Trig
Find the radian measure of the central angle of a circle of radius r that intercepts an arc of length s.? Radius, r=16 ft Arc length, s=10 ft
Friday, May 18, 2012 at 12:51pm

graphing trig functions
In that case, pick points that you know. For 2sinx, say, you know that sin 0 = 0 sin pi/6 = .5 sin pi/4 = .707 sin pi/3 = .866 sin pi/2 = 1 and so on If you know a few key values, you can sketch the graph easily. If you don't happen to know the value of pi/3, etc, use ...
Friday, May 18, 2012 at 10:18am

graphing trig functions
but for my quiz, i am not allowed a calculator
Friday, May 18, 2012 at 12:58am

graphing trig functions
You can pick as many x points as you want. The more you plot, the easier it is to plot a smopoth and accurate curve. For the y values that go with each x, you need a calculator, a special slide rule or a table of trig functions. Hardly anyone uses tables or slide rules anymore.
Friday, May 18, 2012 at 12:45am

graphing trig functions
for graphing basic trig functions such as y=2sinx or y=1/3cosx, how do you know what the points are to graph with out using a calculator?
Friday, May 18, 2012 at 12:31am

trig
sinAcosB = 1/2 (sin(A+B) + sin(A-B)) Looks like 1/2(sin6x+sin2x)
Thursday, May 17, 2012 at 11:46pm

trig
write sin4xcos2 as the sum or difference of two functions. answers: 1/2(cos6x+cos2x), 1/2(cos2x-cos6x), 1/2(sin6x+sin2x), sin6x-sin2x
Thursday, May 17, 2012 at 9:38pm

trig
U∘V = |U| |V|cos Ø, where Ø is the angle between 2 - 15 = √13√26cosØ cosØ = -13/13√2 = -1/√2 Ø = 135°
Thursday, May 17, 2012 at 8:07pm

trig function
Oh your right! Now I see that, thanks so much!
Thursday, May 17, 2012 at 7:56pm

trig
The coefficients of sin(x) and -cos(x) are 1 and -1 respectively. We divide each term by the factor sqrt(1²+(-1)²)=sqrt(2) y=sinx-cosx => y=sqrt(2)[sin(x)*(1/sqrt(2)+cos(x)*(-1/s​qrt(2)) Since cos(-π/4)=1/sqrt(2), and sin(-π/4)=-1/sqrt(2), we set a=3&...
Thursday, May 17, 2012 at 7:46pm

trig function
(fxg)(x) = (cosx - sinx)(cosx + sinx) = cos^2 x - sin^2 x = cos 2x , by definition. notice the period of the new one is 2π/2 = π while the period of the first one was 2π notice the compression by a factor of 1/2 ?
Thursday, May 17, 2012 at 7:46pm

trig
write sin4xcos2 as the sum or difference of two functions. answers: 1/2(cos6x+cos2x), 1/2(cos2x-cos6x), 1/2(sin6x+sin2x), sin6x-sin2x
Thursday, May 17, 2012 at 7:18pm

trig
find the angle between vector U=<2,3> and V=<1,-5> answers: 88 degrees, 45 degrees, 135 degrees, or 92 degrees...?
Thursday, May 17, 2012 at 7:13pm

trig function
Suppose f(x)=cos x - sin x and g(x)=cos x + sin x. Explain why the graph of (fxg)(x) is equivalent to the graph of h(x)=cos x after it has been horizontally compressed by a factor of 1/2. Please help, thank you!
Thursday, May 17, 2012 at 7:10pm

trig
ksin(x+a) = k(sinxcosa) + cosxsina) = ksinxcosa + kcosxsina then ksinxcosa + kcosxsina = sinx - cosx , which must be an identity, so true for all x let x =0 k(0)cosa + k(1)sina = 0-1 ksina= 1 sina = 1/k let x = 90° k(1)(cosa) + k(0) = 1-0 cosa = 1/k sina/cosa = (1/k) / (1/...
Thursday, May 17, 2012 at 7:03pm

trig
write y=sinx-cosx in the form y=ksin (x+a), where the measure of a is in radians. answers: sqrt2sin (x+3pi/4), sqrt2sin (x+5pi/4), sqrt2sin (x+pi/4), or sqrt2sin (x+7pi/4) ...?
Thursday, May 17, 2012 at 6:49pm

trig
write sin4xcos2 as the sum or difference of two functions. answers: 1/2(cos6x+cos2x), 1/2(cos2x-cos6x), 1/2(sin6x+sin2x), sin6x-sin2x
Thursday, May 17, 2012 at 6:42pm

trig
when t=0 , all answers with sin are zero all answers with cosine are 4, so we eliminate the sine answers period of a sine or cosine function is 2π/k but we are told: 2π/k = 2 k = π so it must be y = 4cos πt
Thursday, May 17, 2012 at 6:30pm

trig
9π/5 = 2π + π/5 so the "angle in standard position" or the "reference angle"is π/5
Thursday, May 17, 2012 at 6:27pm

trig
make a sketch of a 2-3-√13 right-angled triangle to see that sin[tan^-1 (2/3)] = 2/√13
Thursday, May 17, 2012 at 6:25pm

trig
Write an equation for simple harmonic motion, given that the amplitude equals 4 inches and the period equals 2 seconds and the max displacement occurs when t=0. answers: y=4sin pi t, y=4cos pi t, y=4cos t, y=4sin2 pi t
Thursday, May 17, 2012 at 6:24pm

trig
an angle with the radian measure of 9pi/5. find radian measure of its reference angle. answers: -4/5, 4pi/5, -pi/5, or pi/5
Thursday, May 17, 2012 at 6:21pm

trig
recall cosAcosB - sinAsinB = cos(A+B) then cos6xcosx - sin6xsinx = cos(6x+x) = cos(7x)
Thursday, May 17, 2012 at 6:20pm

trig
what is the exact value of sin[tan^-1(2/3)]
Thursday, May 17, 2012 at 6:19pm

trig
sin a = 15/17 , with a in I, so cos a = 8/17 cos b = 4/5, with b in IV, then sin b = -3/5 cos(a+b) = cosa cosb - sina sinb = (8/17)(4/5) - (15/17)(-3/5) = (32 + 45)/85 = 77/85
Thursday, May 17, 2012 at 6:19pm

trig
would that be 88 degrees, 45 degrees, 135 degrees, or 92 degrees?
Thursday, May 17, 2012 at 6:10pm

trig
cos T = U dot V / ( |U|* |V| ) = (2-15) / (sqrt 13 + sqrt 26) = -13 / (sqrt 13 + sqrt 2 sqrt 13) = -13/ [sqrt 13 (1 + sqrt 2) ]
Thursday, May 17, 2012 at 6:04pm

trig
Yes
Thursday, May 17, 2012 at 6:00pm

trig
sqrt (4 + 9) = sqrt 13 tan T = -2/-3 = 33.7 deg in quad 3 so 33.7 + 180 = 213.7 degrees
Thursday, May 17, 2012 at 6:00pm

trig
16 cos 120 i + 16 sin 120 j cos 120 = -.5 sin 120 = +.866 or (1/2)sqrt 3 so -8 i + 8 sqrt 3 j SKETCH it on a GRAPH !!!!
Thursday, May 17, 2012 at 5:57pm

trig
would the 3 answers be: pi/6, 5pi/6, 3pi/2
Thursday, May 17, 2012 at 5:43pm

trig
2 U = 10 i + 22 j 7 V = 14 i - 21 j ----------------- subtract for 2 U - 7 V = -4 i + 1 j but I have no idea if that is what you want. Please repair typo.
Thursday, May 17, 2012 at 5:41pm

trig
its 2U-7V
Thursday, May 17, 2012 at 5:39pm

trig
2U-7U must be a TYPO maybe 2 U - 7V ? or 2V - 7 U ???
Thursday, May 17, 2012 at 5:37pm

trig
thats the problem i have..? the answers may be: 24i+43, -4i+j, -4i+43j, or 24i+j
Thursday, May 17, 2012 at 5:36pm

trig
Corection: sin ( x ) = 1 / 2 sin ( x ) = - 1
Thursday, May 17, 2012 at 5:34pm

trig
cos ^ 2 ( x ) = 1 - sin ^ 2 ( x ) 2 cos ^ 2 ( x ) - sin ( x ) = 1 2 * [ 1 - sin ^ 2 ( x ) ] - sin ( x ) = 1 2 - 2 sin ^ 2 ( x ) - sin ( x ) = 1 Subtract 1 to both sides 2 - 2 sin ^ 2 ( x ) - sin ( x ) - 1 = 1 - 1 - 2 sin ^ 2 ( x ) - sin ( x ) + 1 = 0 Substitute : sin ( x ) = u...
Thursday, May 17, 2012 at 5:33pm

trig
2 + 2 i sqrt 3 ???? 2 (1 + i sqrt 3) 4 (1/2 + i sqrt(3) /2 ) 4 (cos 60 deg + i sin 60 deg) 4 cis 60 or 4 cis (pi/3)
Thursday, May 17, 2012 at 5:23pm

trig
U=5i+11j and V=2i-3j, find 2U-7U
Thursday, May 17, 2012 at 5:02pm

trig
write 2+2 squareroot of 3i in trig form.
Thursday, May 17, 2012 at 5:01pm

trig
find the angle between vectors U= <2,3> and V= <1, -5>
Thursday, May 17, 2012 at 4:53pm

trig
a vector has a magnitude of 16 and direction of 120 degrees. write the vector in terms of unit vecotrs i and j.
Thursday, May 17, 2012 at 4:52pm

trig
what is the magnitude and direction of the vector U= -2i - 3j
Thursday, May 17, 2012 at 4:50pm

trig
write y=sinx-cosx in the form y=ksin (x+a), where the measure of a is in radians.
Thursday, May 17, 2012 at 4:48pm

trig
solve 2cos^2x-sinx=1, 0 < or equal to x < 2pie
Thursday, May 17, 2012 at 4:47pm

trig
write sin4xcos2 as the sum or difference of two functions.
Thursday, May 17, 2012 at 4:45pm

trig
what's the single trig. function of cos6xcosx-sin6xsinx
Thursday, May 17, 2012 at 4:44pm

trig
Given sin a = 15/17 with a in Quadrant I and cos beta = 4/5 with beta in QuandrantIV, find the exact value of cos(a+beta)
Thursday, May 17, 2012 at 4:43pm

trig function
Suppose f(x)=cos x - sin x and g(x)=cos x + sin x. Explain why the graph of (fxg)(x) is equivalent to the graph of h(x)=cos x after it has been horizontally compressed by a factor of 1/2. Thanks so much...
Thursday, May 17, 2012 at 2:51pm

trig function
Suppose f(x)=cos x - sin x and g(x)=cos x + sin x. Explain why the graph of (fxg)(x) is equivalent to the graph of h(x)=cos x after it has been horizontally compressed by a factor of 1/2. Thanks so much...
Thursday, May 17, 2012 at 2:51pm

trig function
Suppose f(x)=cos x - sin x and g(x)=cos x + sin x. Explain why the graph of (fxg)(x) is equivalent to the graph of h(x)=cos x after it has been horizontally compressed by a factor of 1/2. Thanks so much...
Thursday, May 17, 2012 at 2:50pm

trig
C = 180 - 81 - 50 = 49° b/sin81 = 12/sin49 b = 12sin81/sin49 = ... find a the same way
Wednesday, May 16, 2012 at 11:36pm

trig
let y = -3sin(2t - π/3) = -3sin 2(t - π/6) amplitude = |-3| = 3 period = 2π/2 = π phase shift: π/6 to the right
Wednesday, May 16, 2012 at 11:33pm

trig
what is the amplitude, phase shift, and period of -3sin(2t- pie/3)
Wednesday, May 16, 2012 at 10:56pm

trig
on a triangle, A = 50 degrees, B = 81 degrees, and c = 12. what does a, b, and C equal?
Wednesday, May 16, 2012 at 10:54pm

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