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Help Proving Trigonometic Identity?
I need help proving this identity. Thanks for your help.
(1+cos A+cos 2A) / (sin A + Sin 2A) = cot A
2 Answers
- 1 decade agoFavorite Answer
cot A = ( 1 + cosA + cos 2A )/ (sinA + sin2A)
identities we need to know
1. cot A = cosA/sinA
2, cos 2A = 2cos^2A - 1
3.sin2A = 2 sinAcosA
now let's play
cot A = (1 + cosA + 2cos^2A -1)/(sinA + 2sinAcosA)
= ( cosA + 2cos^2A)/sinA( 1 + 2cosA)
= cosA ( 1 +2 cosA)/ sinA ( 1 + 2cosA)
= cosA/sinA
= cotA
- Anonymous4 years ago
a million) "amplify" cotx: sinx + cosx(cosx / sinx) = a million/sinx multiply sinx by utilising way of (sinx / sinx) to get a familiar base: (sin²x+ cos²x) / sinx = a million/sinx when you consider that sin²x+ cos²x = a million... a million/sinx = a million/sinx the two factors are same
