Thread: Tough 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

Originally Posted by OmegaCenturion

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

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

Originally Posted by OmegaCenturion

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

write this as:



or,







Note that:





You should know that

thanks guys!