Question

if sec 5a is equal to cosec 4A minus 18 find A

Answer 1

Hi !

$\sin(5a) = cosec(4a)$

We know that,

$\sin(90 - \theta) = cosec \: \: \theta$

So,

$cosec \: (90 - 5a) = cosec \: 4a \\ \\ 90 - 5a = 4a \\ \\ 90 = 4a + 5a \\ \\ 9a = 90 \\ \\ a = \frac{90}{9} \\ \\ a = 10$