# Maths

Evaluate in simple surd form the following:
(1) Sin 225
(2) Cos 195
(3) Sin 345
(4) tan 195

1. 👍
2. 👎
3. 👁
1. remember your standard angles and half-angle formulas, then
sin225 = sin(180+45) = -sin45
cos195 = cos(180+15) = -cos15 = -cos(30/2)
sin345 = sin(360-15) = -sin15
tan195 = tan(180+15) = tan15 = tan(30/2)

1. 👍
2. 👎
2. Aye

1. 👍
2. 👎

## Similar Questions

1. ### calculus

Find complete length of curve r=a sin^3(theta/3). I have gone thus- (theta written as t) r^2= a^2 sin^6 t/3 and (dr/dt)^2=a^2 sin^4(t/3)cos^2(t/3) s=Int Sqrt[a^2 sin^6 t/3+a^2 sin^4(t/3)cos^2(t/3)]dt =a Int

2. ### math

Can you please check my work. A particle is moving with the given data. Find the position of the particle. a(t) = cos(t) + sin(t) s(0) = 2 v(0) = 6 a(t) = cos(t) + sin(t) v(t) = sin(t) - cos(t) + C s(t) = -cos(t) - sin(t) + Cx + D

3. ### Trig

Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are in quadrant 1. =Sin(s)cos(t) + Cos(s)Sin(t) =Sin(1/5)Cos(3/5) + Cos(-1/5)Sin(3/5) = 0.389418 Sin(s-t) =sin(s)cos(t) - cos(s)sin(t) =sin(-3/5)cos(1/5) -

What are the ratios for sin A and cos A? The diagram is not drawn to scale. Triangle Description- AB = 29 AC = 20 BC - 21 A. sin A = 20/29, cos A = 21/29 B. sin A = 21/29, cos A = 20/21 C. sin A = 21/29, cos A = 20/29****? D. sin

1.)Find dy/dx when y= Ln (sinh 2x) my answer >> 2coth 2x. 2.)Find dy/dx when sinh 3y=cos 2x A.-2 sin 2x B.-2 sin 2x / sinh 3y C.-2/3tan (2x/3y) D.-2sin2x / 3 cosh 3yz...>> my answer. 2).Find the derivative of y=cos(x^2) with

2. ### trig

The expression 4 sin x cos x is equivalent to which of the following? (Note: sin (x+y) = sin x cos y + cos x sin y) F. 2 sin 2x G. 2 cos 2x H. 2 sin 4x J. 8 sin 2x K. 8 cos 2x Can someone please explain how to do this problem to

3. ### calculus

Find the points on the curve y= (cos x)/(2 + sin x) at which the tangent is horizontal. I am not sure, but would I find the derivative first: y'= [(2 + sin x)(-sin x) - (cos x)(cos x)]/(2 + sin x)^2 But then I don't know what to

4. ### Calculus AP

Evaluate the integral interval from [0 to pi] t sin(3t)dt Use integration by parts u=t and dv=sin(3t)dt. then du=dt and v=-cos(3t)/3 here is my problem but Im having problem to solve with pi. ∫t sin(3t)dt = -tcos(3t)/3 -

1. ### math

Proving Trigonometric Identities 1. sec^2x + csc^2x= (sec^2 x)(csc^2 x) 2. sin ^3 x / sin x - cos 3x / cos x = 2 3. 1- cos x/ sin x= sin x/ 1+ cos x 4. 2 sin x cos ^2 (x/2)- 1/x sin (2x) = sinx 5. cos 2 x + sin x/ 1- sin x= 1+ 2

2. ### Trig (math)

1.) Write the complex number in trigonometric form r(cos theta + i sin theta) with theta in the interval [0°, 360°). 9 sqrt 3 + 9i 2.) Find the product. Write the product in rectangular form, using exact values. [4 cis 30°] [5

3. ### math, calculus

Interference Two identical tuning forks are struck, one a fraction of a second after the other. The sounds produced are modeled by f1(t) = C sin ωt and f2(t) = C sin(ωt + α). The two sound waves interfere to produce a single

4. ### Trig

If angle A is 45 degrees and angle B is 60 degrees. Find sin(A)cos(B), find cos(A)sin(B), find sin(A)sin(B), and find cos(A)cos(B) The choises for the first are: A. 1/2[sin(105)+sin(345)] B. 1/2[sin(105)-sin(345)] C.