Question

$\frac{1}{\cos \theta }=$_____ , for an acute angle $\theta$ in a right angled triangle.

• A. $\text{cosec}\theta$
• B. $\sec \theta$
• C. $\cot \theta$
• D. None of these

Answer 1

The correct option is B $\sec \theta$

$\sin \theta =\frac{opposite}{hypotenuse}$

$\cos \theta =\frac{adjacent}{hypotenuse}$

$\frac{1}{\cos \theta }=\frac{1}{\frac{adjacent}{hypotenuse}}=\frac{hypotenuse}{adjacent}=\sec \theta$

$\therefore \frac{1}{\cos \theta }=\sec \theta$