Question

Evaluate 1 – 2$sin\theta$ $cos\theta$ if $sin\theta$ = $cos\theta$.

• A. - 1
• B. 0
• C. 2
• D. 1

Answer 1

The correct option is B

0

We can write 1 as $si{n}^2\theta$ + $co{s}^2\theta$

Therefore, 1 - 2$sin\theta$ $cos\theta$ = $si{n}^2\theta$ + $co{s}^2\theta$ - 2$sin\theta$ $cos\theta$

= $(sin\theta -cos\theta {)}^2$

If $sin\theta$ = $cos\theta$, $(sin\theta -cos\theta {)}^2$ = 0