Question

6.Prove that tan y cos^2 y + sin^2y/sin y = cos y + sin y

10.Prove that 1+tanθ/1-tanθ = sec^2θ+2tanθ/1-tan^2θ

17.Prove that sin^2w-cos^2w/tan w sin w + cos w tan w = cos w-cot w cos w

23.Find a counterexample to shows that the equation sec a – cos a = sin a sec a is not an identity.

Answer 1

you gotta add some parentheses, so we can tell what's the numerator and what's the denominator.

For #23, just pick an easy value, like pi/4:

√2 - 1/√2 =?= 1/√2 * √2
No.