- Given: sinθ+cosθ=27
- Let's square this equation:
(sinθ+cosθ)2=47
sin2θ+2sinθcosθ+cos2θ=47
Since sin2θ+cos2θ=1:
1+2sinθcosθ=47
2sinθcosθ=43 ...(1)
- Now for sinθ−cosθ, let's square:
(sinθ−cosθ)2
=sin2θ−2sinθcosθ+cos2θ
=1−2sinθcosθ
- From equation (1):
(sinθ−cosθ)2
=1−43
=41
- Therefore:
sinθ−cosθ=±21
- Since sinθ+cosθ=27 is positive,
sinθ−cosθ=21