Question

evaluate exactly(without calculator):
1. sec(pi/4)

2.3sin4pi

3. tan240(degrees)

Answer 1

1. Cos(pi/4)= cos 45 degrees = 1/sqrt2
What does that tell you about sec(pi/4)?

2. sin 4 pi = sin 0 - ___

3. tan 240 deg = tan 60 deg = ___

Answer 2

cos pi/4 = cos 45 degrees = sqrt 2/2
so
sec = 1/cos = 2/sqrt 2 = 2 sqrt 2

sin 4 pi = sin 0 (twice all the way around ) = 0

240 = 180 + 60
in quadrant 3, x is - , y is -
so tangent is +
tan 60 = (sqrt 3)/1 = sqrt 3