Find the exact value of each sin 210 degree cos 150 degree t

Find the exact value of each: sin 210 degree cos 150 degree tan 135 degree sin 7 pi/4

Solution

1) sin210

= sin(180+30)

= -sin30 = -1/2 = -0.5

2) cos150

= cos(180 -30)

= -cos30

= -sqrt3/2

3) tan135

= tan (90+45)

= -tan45

= -1

4) sin(7pi/4)

= sin( 2pi - pi/4)

= -sinpi/4

= -1/sqrt2