Question

Find the value of $({\sec }^2{10}^{\circ }-{\cot }^2{80}^o)=$

• A. $1$
• B. $0$
• C. $\frac{3}{2}$
• D. None of above

Answer 1

The correct option is A $1$

Given,

$\left({\sec }^2{10}^o-{\cot }^2{80}^o\right)$

$=\left({\sec }^2{10}^o-{\cot }^2({90}^o-{10}^o)\right)$

$={\sec }^2{10}^o-{\tan }^2{10}^o=1$

Hence $1$ will be the answer