Question

Find the value of $\theta$, if the equation $cos\theta x^2-2sin\theta x-cos\theta =0$ real root.

• A. π/4
• B. π/2
• C. -π/4
• D. -π/3

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A

π/4

B

π/2

C

-π/4

D

-π/3

Discriminant = $4(-2sin\theta {)}^2-4$ x $cos\theta$ x $-cos\theta \left)\right)$
$=4si{n}^2\theta +4co{s}^2\theta$
$=4(si{n}^2\theta +co{s}^2\theta )$
$=4$
$\Rightarrow △>0$
$\Rightarrow$ Given equation has real roots for all value of $\theta$