Question

Can anyone please solve this.Trignometry 10​

Answer 1

Given

1-tan²∅/1+tan²∅

To show

Cos²∅-sin²∅

Proof

Breaking tan²∅= sin²∅/cos²∅

$\implies\frac{1-\frac{sin^2\theta}{cos^2\theta}}{1+tan^2\theta}$

we know that

1+tan²∅=sec²∅

$\implies\huge\sf\frac{1</p><p>\frac{-sin^2\theta+cos^2\theta}{cos^2\theta}}{sec^2\theta}$

$\implies\sf\huge\frac{\frac{-sin^2\theta+cos^2\theta}{cos^2\theta}}{\frac{1}{cos^2\theta}}$

=>Cos²∅-sin²∅

Hence, proved