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8. Introduction to Trigonometry
easy
यदि $\sin \alpha=\frac{1}{2}$ और $\cos \beta=\frac{1}{2}$ दिया है, तो $(\alpha+\beta)$ का मान है
A
$0^{\circ}$
B
$90^{\circ}$
C
$30^{\circ}$
D
$60^{\circ}$
Solution
Given, $\quad \sin \alpha=\frac{1}{2}=\sin 30^{\circ}$ $\left[\because \sin 30^{\circ}=\frac{1}{2}\right]$
$\Rightarrow \quad \alpha=30^{\circ}$
and $\quad \cos \beta=\frac{1}{2}=\cos 60^{\circ}$ $\left[\because \cos 60^{\circ}=\frac{1}{2}\right]$
$\Rightarrow \quad \beta=60^{\circ}$
$\therefore \quad \alpha+\beta=30^{\circ}+60^{\circ}=90^{\circ}$
Standard 10
Mathematics
