Question

formula for cos²∅ tell me fast

Answer 1

formula of cos²∅
= 1 - sin²∅

Answer 2

you didn't identify which formula of cos²∅ , you want .

I am giving some formula which may help you for solving Questions :-

1) cos²∅ = 1/sec²∅
2) cos²∅ = 1 - sin²∅
3) cos²∅ = 1/( 1 + tan²∅)
4)cos²∅ = cot²∅/(1 + cot²∅)
5)cos²∅ = ( 1 + cos2∅)/2
6) cos²∅ = (cosec²∅ -1)/cosec²∅
7)cos²∅ = (1 - cos2∅)/tan²∅
8)cos²∅ =(1 - cos2∅)/(sec²∅ -1)