Sin x=sin 60 · cos 30-cos 60 · sin 30, then x=ldots ldots ldots ldots

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8. Introduction to Trigonometry

easy

$\sin x=\sin 60 \cdot \cos 30-\cos 60 \cdot \sin 30,$ then $x=\ldots \ldots \ldots \ldots$

A

$0$

B

$30$

C

$45$

D

$60$

Solution

$\sin x=\sin 60 \cdot \cos 30-\cos 60 \cdot \sin 30$

$=\frac{\sqrt{3}}{2} \cdot \frac{\sqrt{3}}{2}-\frac{1}{2} \cdot \frac{1}{2}=\frac{3}{4}-\frac{1}{4}=\frac{2}{4}=\frac{1}{2}$

$\therefore \sin x=\frac{1}{2} \cdot$ But, $\sin 30=\frac{1}{2} \, \therefore x=30$

Standard 10

Mathematics

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