# maths trig

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#1
prove that (sin3x+cos3x)^2 = 1+sin6x (an identity )

please can someone help I'm really struggling
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1 month ago
#2
(Original post by jessiepip)
prove that (sin3x+cos3x)^2 = 1+sin6x (an identity )

please can someone help I'm really struggling
OK so first expand the bracket on the left as if you were doing (A+B)^2
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#3
(Original post by davros)
OK so first expand the bracket on the left as if you were doing (A+B)^2
okay, thank you , i've done that and I've then simplified some of it down and i ended up with 3+ sin6x , I'm not sure where I've gone wrong or how to get the +1
0
1 month ago
#4
(Original post by jessiepip)
okay, thank you , i've done that and I've then simplified some of it down and i ended up with 3+ sin6x , I'm not sure where I've gone wrong or how to get the +1
Where have you got the '3' from? sin^2A + cos^2A = 1 for any angle A
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