$\sin 10° \cdot \sin 50° \cdot \sin 70°$
Using identity: $\sin\theta \cdot \sin(60°-\theta) \cdot \sin(60°+\theta) = \frac{\sin 3\theta}{4}$
$$= \frac{\sin 30°}{4} = \frac{1/2}{4} = \frac{1}{8}$$
Back to JEE Main 2025 Trigonometry
JEE Main 2025 — Mathematics Trigonometry
easy
mcq
2025
Official previous-year question
Verified 30 May 2026.
Question
The value of $\sin\frac{\pi}{18} \cdot \sin\frac{5\pi}{18} \cdot \sin\frac{7\pi}{18}$ is:
Options
- A
$\frac{1}{8}$
- B
$\frac{1}{4}$
- C
$\frac{\sqrt{3}}{8}$
- D
$\frac{1}{2}$
Solution
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