Question

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

Answer 1

(1+sin a)(1-sin a)/(1+cos a)(1-cos a)=. (1-sin^2 a)/(1-cos^2 a) = cos^2 a/sin^2 a = cot^2 a =289/324=0.891

Answer 2

Answer:

Step-by-step explanation:

The given equation is:

$\frac{(1-sina)(1+sina)}{(1-cosa)(1+cosa)}$

which can be simplified as:

=$\frac{1-sin^2a}{1-cos^2a}$

=$\frac{cos^2a}{sin^2a}$

=$(cota)^2$

Now, we are given that $cot a=\frac{17}{18}$, therefore the abpove equation becomes,

=$(\frac{17}{18})^2$

=$\frac{289}{324}$

=$0.891$

which is the required simplified form.