# sin and cosine function

• Mar 14th 2013, 01:38 PM
calmo11
sin and cosine function
Attachment 27525
Please need help with this question!
• Mar 14th 2013, 01:40 PM
Siron
Re: sin and cosine function
Use $(a+b)^2 = a^2+2ab+b^2$.
• Mar 14th 2013, 04:06 PM
calmo11
Re: sin and cosine function
I tried doing this and i ended up with 2sin(a)cos(a)=0 where a=alpha, but i am not too sure where to go from there?
• Mar 14th 2013, 11:44 PM
MINOANMAN
Re: sin and cosine function
Calmo
Study trigonometry a little bit. you have to know that 2sinacosa=sin(2a)
therefore you have to solve the equation sin(2a)=0 which is very easy...
• Mar 15th 2013, 01:41 AM
ibdutt
Re: sin and cosine function
OK
2 sin A cos A = 0 that is when sinA = 0 or cos A = 0
sin A = 0 when A = 0 or pi and cos A = 0 when A = pi/2
I am sure you can finish it now