To find the answer, you need to divide 90.5 by 4. The answer to that is 22.625, and if you want to check the answer, 22.625 x 4 = 90.5. Hope this helps :)
if you're wondering about the restriction of x ≠ -4, is due to that would make the fraction with a denominator of 0 and thus undefined.
<u>Answer and explanation</u>
(1+sinθ)(1-sinθ)=cos²θ
We are to prove that the left hand side is equal to the right hand side.
(1+sinθ)(1-sinθ) = 1(1-sinθ) + sinθ(1-sinθ)
= 1 - sinθ + sinθ - sin²θ
= 1 - sin²θ
From the trigonometric identity sin²θ + cos²θ = 1,
1 - sin²θ = cos²θ