Homework Help: Trigonometric functions

Posted by Jon on Sunday, February 10, 2008 at 5:13pm.

1)Which angle is coterminal with a -400 degree angle in standard postion?
A)40
B)80
C)320
D)400
I chose A

(for the next one I dont know what its called but it looks like 0 with a horizontal line through the middle.)

2)Find the exact value of cos looks like 0 with a horizontal line through the middle if the terminal side of 0 with a horizontal line through the middle in standard postion contains the point (6,-8).
A)-4/5
B)3/5
C)4/5
D)-3/5
I chose B

Trigonometric functions - Damon, Sunday, February 10, 2008 at 5:26pm
plus or minus all the way around or 360 changes nothing, so add 360 first
-400 + 360 = -40
well usually standard is counterclockwise from the x axis so
-40 = 360 -40 = 320
I would choose C

2,
That is called THETA but I will call it T
It is in the fourth quadrant between 270 and 360
the hypotenuse of this 3,4,5 triangle = 2*5 = 10
the cosine = adjacent/hypotenuse = +6/10==+3/5
B = agree
Trigonometric functions - Alex, Sunday, February 10, 2008 at 5:26pm
C for the first one. All of them aside from 320 lie in Quadrant 1. 320 and -400 lie in Quadrant 4. Since 400 is negative it moves clockwise, when the other angles move counterclockwise.

I'm not sure what you're asking in the 2nd. The exact value of cos theta with a horizontal line through the middle of the angle?
Trigonometric functions - Reiny, Sunday, February 10, 2008 at 5:34pm
Remember a negative angle is a clockwise rotation, so a -400º angle goes all the way around and down another 40º into the fourth quadrant.
Using the standard notation that would be an angle of 320º

for your second question you are probably looking at cosθ, or cos theta.
Theta is often used as the variable to represent an angle and is one of the Greek letters.

So draw a triangle by joining the origin to the point (6,-8), which is the fourth quadrant
cosθ = adjacent/hypotenuse
hypotenuse = √(6^2 + (-8)^2) = 10
adjacent = 6

so cosθ = 6/10 = 3/5

Answer this Question

Related Questions

Algebra II - 1)Rewrite 5pi/4 radians in degree measure. Answer: 225 2) Which ...
Math- Trigonometry - The point, in on the terminal side of an angle in standard ...
math - Find an angle between 0 degree and 360 degree that is coterminal with ...
Trigonometric functions - 1)I have a right triangle. the hypotenuse is 7 the ...
Johan - Given angle 1 = (x + 7)degree, angle 2 = *(2x -3)degree, angle ABC = (x ...
Precalculus - Evaluate all six trigonometric functions at t, where the given ...
math - trigonometric functions/ radians the angle Ə is in the first ...
Precalculus Someone please help - Evaluate all six trigonometric functions at t...
Geometry - Angle Construction - I need to construct a 75 degree angle. I was ...
trig - find the reference angle of -20000 and express the six trigonometric ...

For Further Reading

First Name:
School Subject:
Answer: