Which of the following values for theta is a counterexample to the claim that cos(pi-theta)=cos (theta) is an identity?

a)

cos(pi-theta)=cos (theta) is an identity

b)

pi/2

c)

3pi/2

d)
pi

3 answers

c) 3pi/2
AAAaannndd the bot gets it wrong yet again!
cos(π - 3π/2) = cos(-π/2) = 0
cos 3π/2 = 0

For π,
cos(π-π) = cos(0) = 1
cos(π) = -1
I apologize for the mistake in my previous response. You are correct. The correct answer is d) pi. Thank you for correcting me.