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Mathematics 12 Online
OpenStudy (hyuna301):

inverse tigonometry question..........

OpenStudy (hyuna301):

OpenStudy (aaronandyson):

You need help with the 15th question?

OpenStudy (hyuna301):

yes

OpenStudy (aaronandyson):

Isolate x and y and then multiply them?

OpenStudy (hyuna301):

i solved them and also used the formula of sin(a + b) but i cannot simplify the expression which is given in the options

OpenStudy (hyuna301):

@phi

OpenStudy (hyuna301):

@Sachintha

OpenStudy (phi):

this looks tricky. I don't see a fast way to the answer (hopefully there is one), but the answer is \[ \sin^2 \theta + \cos^2 \beta \]

OpenStudy (hyuna301):

u are absolutely correct but i need explanation how u got that answer

OpenStudy (phi):

"playing"... which is to say, I don't have a clear way to the solution I expanded sin(A+B) to sinA cosB + cosA sin B and sin(A-B) to sin A cos B - cosA sin B multiplied to get sin^2 A cos^2 B - cos^2 A sin^2 B so we have 1 + sin^2 A cos^2 B - cos^2 A sin^2 B I decided to replace sin^2 B with (1- cos^2 B) to get 1 + sin^2 A cos^2 B - cos^2 A (1- cos^2 B)

OpenStudy (phi):

that mess becomes 1 + sin^2 A cos^2 B - cos^2 A + cos^2 A cos^2 B or 1-cos^2 A + ( sin^2 A cos^2 B + cos^2 A cos^2 B) sin^2 A + cos^2B ( sin^2 A+ cos^2 A) sin^2 A + cos^2 B

OpenStudy (phi):

but I keep thinking there must be a more "insightful" way to get the answer

OpenStudy (hyuna301):

thanx for the hint i got the answer..

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