Hey again,
I have these three particular questions that I can’t get answer, i just float around it but never close to the bullseye.
- sin (P + Q) cos (P + R) - cos (P + Q) sin (P + R)
- cos (x + y) cos x + sin (x + y) . sin x
- sin (A + B - C) cos (A - B + C) + cos (A + B - C) . sin (A - B + C)
the rules relating to this are:
-> sin (a + b) = sina cosb + cosa sinb
-> sin (a - b) = sina cosb - cos a sinb
-> cos (a + b) = cosa cos b - sina sinb
-> cos (a - b) = cosa cosb + sina sinb
Do I collect the like terms and then expand them or do I multiply how it is, expand it and then collect like terms? Some help would be great.
