Question

`(sinA.tanA)/(1 - cos A) - 1` is equal to ______.

विकल्प

• cosec А

• sec A

• sin A

• tan A

Answer 1

`(sinA.tanA)/(1 - cos A) - 1` is equal to sec A.

Explanation:

We know,

tan A = `sin A/cos A`

`(sin A.(sin A/cos A))/(1 - cos A) - 1`

`(sin^2 A/cos A)/(1 - cos A) - 1`

cos A  from the numerator to the denominator:

`sin^2 A/(cos A(1 - cos A)) - 1`

`(1 + cos A)/cos A- 1`

`(1/ cos A + cos A/cos A) - 1`

sec A + 1 − 1

sec A