Question

The value of $sin({50}^o+\theta )-cos({40}^o-\theta )=$ _____.

• A. $1$
• B. $-1$
• C. $2$
• D. $0$

Answer 1

Answer: (D)

$0$

$\sin (50+\theta )-\cos (40-\theta )$
$=\sin (90-40+\theta )-\cos (40-\theta )$
$=\sin [90-(40-\theta \left)\right]-\cos (40-\theta )$

$=cos(40-\theta )-cos(40-\theta )...........................since\sin (90-\theta )=cos\theta$

$=0$