Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# Write the Least Value of Cos2 X + Sec2 X. - Mathematics

Write the least value of cos2 x + sec2 x.

#### Solution

We know:
cos x can take the minimum value of -1.
cos2 x + sec2 x
$= \frac{\cos^4 x + 1}{\cos^2 x}$
$= \frac{\left( - 1 \right)^4 + 1}{\left( - 1 \right)^2}$
$= 2$

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#### APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 5 Trigonometric Functions
Q 15 | Page 41