I'm not strong with this, i need some help:

2(1-sin(b)sin(c)) = cos^2(b) + cos^(c) when b+c = 180

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- Apr 2nd 2010, 10:47 AMOmegaCenturionTough question
I'm not strong with this, i need some help:

2(1-sin(b)sin(c)) = cos^2(b) + cos^(c) when b+c = 180 - Apr 2nd 2010, 10:58 AMArchie Meade
Your clue lies in "b+c=180 degrees", as now c=180-b.

sin(angle) gives the vertical co-ordinate in a circle of radius 1, centre (0,0).

Hence sin(b)=sin(180-b).

Therefore your equation becomes

Using similar logic

allows you to write the entire equation in terms of any one of the four of

sinc, sinb, cosc, cosb

with etc - Apr 2nd 2010, 11:08 AMharish21
- Apr 2nd 2010, 11:36 AMOmegaCenturion
thanks guys!