Question

If $sin{\theta }_1+sin{\theta }_2+sin{\theta }_3=3$, then $cos{\theta }_1+cos{\theta }_2+cos{\theta }_3$ is equal to

• A. $3$
• B. $2$
• C. $1$
• D. $0$

Answer 1

Answer: (D)

$0$

Given: $sin{\theta }_1+sin{\theta }_2+sin{\theta }_3=3$

$\Rightarrow sin{\theta }_1=sin{\theta }_2=sin{\theta }_3=1$..............$(sin90=1)$

$\Rightarrow {\theta }_1={\theta }_2={\theta }_3$

$\therefore cos{\theta }_1+cos{\theta }_2+cos{\theta }_3=0$.............$(cos90=0)$