Thread: trig problem

hi ive been given this question and im not sure how to do it.

1. a) Prove that cosec^4 x - cot^4 x = cosec^2 x + cot^2 x
b) solve for 90 degrees< x < 180 degrees

cosec^4 x - cot^4 x = 2 - cot x

thanks

Originally Posted by brooksy

hi ive been given this question and im not sure how to do it.

1. a) Prove that cosec^4 x - cot^4 x = cosec^2 x + cot^2 x
b) solve for 90 degrees< x < 180 degrees

cosec^4 x - cot^4 x = 2 - cot x

thanks

cosec^4x-cot^4x=(cosec^2x)^2-(cot^2x)^2
=(cosec^2x+cot^2x)(cosec^2x-cot^2x)
=(cosec^2x+cot^2x)
{a^2-b^2=(a-b)(a+b) and cosec^2x-cot^2x=1}

thanks for that. does anyone know how to do part 2. cheers

Originally Posted by brooksy

hi ive been given this question and im not sure how to do it.

b) solve for 90 degrees< x < 180 degrees

cosec^4 x - cot^4 x = 2 - cot x

thanks