We'll recognize to denominator the double angle
identity:
2 sin x*cos x = sin
(2x)
We'll expand the binomial from
numerator:
(sin x)^2 + 2sin x*cos x + (cos
x)^2
We'll use the Pythagorean identity and we'll
get:
(sin x)^2 + (cos x)^2 =
1
The numerator will become:
1
+ sin (2x)
Now, we'll re-write the
fraction:
(sinx + cosx)^2/(1+ 2*sin*x*cos x) = [1 + sin
(2x)]/[1 + sin (2x)]
(sinx + cosx)^2/(1+ 2*sin*x*cos x) =
1
The simplified fraction gives:(sinx +
cosx)^2/(1+ 2*sin*x*cos x) = 1
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