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8. Introduction to Trigonometry
easy
यदि $\cos A =\frac{4}{5}$ है, तो $\tan A$ का मान है
A
$\frac{3}{4}$
B
$\frac{3}{5}$
C
$\frac{4}{3}$
D
$\frac{5}{3}$
Solution
Given, $\cos A=\frac{4}{5}$
$\therefore \quad \sin A=\sqrt{1-\cos ^{2}A}$
$=\sqrt{1-\left(\frac{4}{5}\right)^{2}}=\sqrt{1-\frac{16}{25}}=\sqrt{\frac{9}{25}}=\frac{3}{5}$
Now, $\quad \tan A=\frac{\sin A}{\cos A}=\frac{5}{4}=\frac{3}{4}$
Hence, the required value of tan $A$ is $\frac{3}{4}$
Standard 10
Mathematics