Question

$\cos {12}^{\circ }-\sin {78}^{\circ }=$

• A. $1$
• B. $\frac{1}{2}$
• C. $0$
• D. $-1$

Answer 1

Answer: (C)

$0$

$\cos {12}^{\circ }=\sin {(90-12)}^{\circ }=\sin {78}^{\circ }$

So, $\cos \left({12}^{\circ }\right)-\sin \left({78}^{\circ }\right)=\sin \left({78}^{\circ }\right)-\sin \left({78}^{\circ }\right)=0$