Question

please tell the ans of eighth question

Answer 1

Please refer to the figure...

$\sin\alpha = \frac{3}{5}$
$\tan\alpha = \frac{3}{\sqrt{5^2 - 3^2}}$
$\tan\alpha = \frac{3}{4}$

$\text{or, } \frac{AB}{BC} = \frac{3}{4}$

It means AB : BC = 3 : 4
But from the figure AB = 4
$\therefore BC = \frac{4\times4}{3}$
$\text{or, } BC = \frac{16}{3}$

$\cos\beta = \frac{12}{13}$
$\tan\beta = \frac{\sqrt{13^2-12^2}}{12}$
$\tan\beta = \frac{5}{12}$

$\text{or, } \frac{ED}{CD} = \frac{5}{12}$

It means ED : CD = 5 : 12
But from the figure ED = 3
$\therefore CD = \frac{12\times3}{5}$
$\text{or, } CD = \frac{36}{5}$

From the figure BD = BC + CD
$BD = \frac{16}{3} + \frac{36}{5}$
$BD = \frac{188}{15}$