Question

i didn't understand this step please help​

Answer 1

Here's yours answer

In the step you mention cot A +cosec A was taken as common.

For better understanding lets only consider the numerator here as there was no change in the denominator.

The question was like:

(cot A+ cosec A)-[(cosec A +cot A)(cosec A- cot A)]

Observe that there is a cosec A + cot A both before the minus sign and after it. Let us consider it as X for better understanding.

That makes our previous statement equal to:

(X)-[(X)×(cosec A - cot A)]

Here let us take X as common

a(b+c)=ab+ac.we are just using the converse of this statement.

So we get X[(1)-(cosec A-cot A)]

Which is equal to

X[1-(cosec A -cot A)]

Let us substitute X=cosec A + cot A here

So tge final answer is

cosec A+ cot A(1-(cosec A-cot A))

Just as in your text

Hope it helps

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