Question

If sintheta +costheta=1 then prove 2sintheta-costheta =2

Answer 1

sinA+cosA=1

SO cosA=1-sinA...........(1)

2sinA-cosA=2
Substituting eq no 1
2sinA-(1-sinA)=2
2sinA+sinA=3
3sinA=3
sinA=1
so cosA=0
Substituting the values in the equation...
2(1)-0=2
∴Hence Proved