Question

Verify the identity. cot ( theta - pi / 2 ) = - tan theta

Answer 1

I know cos(theta)+sin(1)= Sin(theta)

Answer 2

Working with Sin(theta-pi/2)

Answer 3

See enclosed

Answer 4

I see. I was researching problem further and found this \[\sin(\theta-\pi/2)=\sin(\theta)\cos(\pi/2)-\cos \theta \sin (\pi/2)\]........... Question from where did the \[\cos(\pi/2) \] by itself come from in the second half of the equation.

Answer 5

This is a standard trigonometric identity

sin(A-B)=sin(A)cos(B)-cos(A)sin(B)

Answer 6

Thank you!!

Answer 7

this was an angle sum and difference identity. I get it now.