# trig

posted by Anonymous

Find the exact value. Without using a calculator

a) cos (-17pi/6)

b) sec (3pi/2)

1. Damon

17/6 = 2 5/6

that is twice around counterclockwise then -5pi/6
that is pi/6 below -x axis
and pi/6 = 180/6 = 30 deg
so 30 deg below -x axis
cos of that is -sqrt3/2

3 pi/2 is 180 + 90 = 270 or on -y axis
undefined

## Similar Questions

1. ### trigonometry

Find the exact value of each expression(no calculator): 1) sin^2(30degrees) + 1/sec^2(20degrees) 2) sec(50degrees)*cos(50degrees)
2. ### trig

Evaluate giving exact values and identities. Calculator based solutions are not acceptable. Thanks for any help cos (4pi/3 – 3pi/4)
3. ### algebra

Evaluate giving exact values and identities. Calculator based solutions are not acceptable. Thanks for any help cos (4pi/3 – 3pi/4)
4. ### trig

Find exact value of the expression. sin( 27pi/4 + 17pi/6)
5. ### Trig

1. Establish the identity: sin(theta+3pi/2)=-cos(theta) 2. Find the exact value of 2(theta) if sin(theta)=5/13 3. Show that: csc2(theta)-cot2(theta)=tan(theta) 4. Find the exact value of tan(cos^-1(square root of 3/2) 5. Approximate …
6. ### 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
7. ### Trig

Use a half-angle identity to find the exact value for sec(x/2) if sinx = -12/13 ; 3pi/2 < x < 2pi