10th Class Mathematics Introduction to Trigonometry Question Bank MCQs - Introduction to Trigonometry

Value of \[(1+\sin A)\,(\sec A-\tan A)=\]

A) \[\sin A\]

B) \[\cos A\]

C) \[\tan A\]

D) \[\sec A\]

Correct Answer: B

Solution :

[b] \[(1+\sin A)(\sec A-\tan A)=(1+\sin A)\,\,\left( \frac{1}{\cos A}-\frac{\sin A}{\cos A} \right)\]

\[=(1+\sin A)\frac{(1-\sin A)}{\cos A}=\frac{1-{{\sin }^{2}}A}{\cos A}=\frac{{{\cos }^{2}}A}{\cos A}=\cos A\]