Question

Which are true?
a. tan^2 x + sec^2 x = 1
b. cos2a=1 - 2sin^2 a
c. cos a/2 = + square root of 1 - cos a/ 2

Answer 1

option b. cos2a=1 - 2sin^2 a is the correct answer.

Answer 2

so the others are both false?

Answer 3

Yes options a and c are false