Question

(1+sinΘ)(1-sinΘ)=cos^2Θ

Answer 1

Help pls how do i make left side of the equation to equal to the right side

Answer 2

hello

Answer 3

Just expand the left hand side and you'll see it in fact is true

\[\large (1 + sin\theta)(1 - sin\theta)\]
\[\large 1 - sin\theta + sin\theta - sin^2\theta\]
\[\large 1 - sin^2\theta\]

So we have

\[\large 1 - sin^2\theta = cos^2\theta\]

Is this true? What do we know from the trig identity \(\large sin^2\theta + cos^2\theta = 1\)

Answer 4

ohh I see now!\

Answer 5

so it is expandable!

Answer 6

thanks

Answer 7

No problem!

Answer 8

i thought i had to use identities lol

Answer 9

for these trig proofs you can use identities or expand... there are a lot of methods to try and make the left hand side = right hand side. It's just that some trig proofs are easier than others.