Question

if cot a =17/18 , evaluate (1+sin a)(1-sin a)/(1+cos a)(1-cos a)

Answer 1

ans this question is 289 / 324

Answer 2

QUESTION :

IF CotA = 17/18.

To find :

(1 + SinA)(1 - SinA)/(1 + CosA)(1 - CosA)

ANSWER:

=(1 + SinA)(1 - SinA) / (1 + CosA)(1 - CosA)

= 1 - Sin^2 A / 1 - Cos^2 A ------->

【 Since, (a + b)(a - b) = a^2 - b^2.(formula)】

= Cos^2 A / Sin^2 A. -------->

【 Since, (Sin^2 A + Cos^2 A = 1) {formula}】

= (CosA / SinA)^2

= (Cot)^2

Putting the value of given 'CotA', we get

= (17/18)^2

= 289/324.

SO, OUR REQUIRED ANSWER IS

= 289/324