First slide

Trigonometric equations

Question

The number of values of satisfying the condition $\sin x + \sin 5 x = \sin 3 x$ in the interval $[0, π]$ is

Moderate

A

6
B

2
C

10
D

0

Solution

$\begin{array}{l} 2 \sin 3 x \cos 2 x = \sin 3 x \\ \Rightarrow \sin 3 x (2 \cos 2 x - 1) = 0 \\ \Rightarrow \sin 3 x = 0 or 2 \cos 2 x = 1 \\ \Rightarrow x = 0, π / 3, 2 π / 3, π \\ or x = π / 6, 5 π / 6 as x \in [0, π] \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App