Question

The value of $[{\sin }^2{20}^{\circ }+{\sin }^2{70}^{\circ }-{\tan }^2{45}^{\circ }]$ is:

• A. $0$
• B. $1$
• C. $2$
• D. $-1$

Answer 1

Answer: (A)

$0$

${\sin }^2{20}^o+{\sin }^2{70}^o-ta{n}^2{45}^o={\sin }^2{20}^o+{\sin }^2({90}^o-{20}^o)-{\tan }^2{45}^o={\sin }^2{20}^o+{\cos }^2{20}^o-{\tan }^2{45}^o=1-1=0$

Therefore, Answer is $0$