Question

What would be the value of Sin(50 + A) - Cos(40 - A), share your working also?

Answer 1

sin(A+B)=sinA cosB+cosAsinB
cos(A-B)=cos AcosB+ sinA sinB
so the right answer is= 0

Answer 2

cos x=sin (90-x)
therefore cos(40-A)=sin(90-(40-A))=sin(50+A) substitute in the original equation
sin (50+A)-sin(50+A)=0

Answer 3

Sin (50 + A) = sin50 cosA + cos50 Sin A
Cos (40 - A) = cos40 CosA + sin 40 Sin A

so
Sin (50+A) - Cos (40 - A) = Cos A ( Sin 50-Cos40) + SinA(Cos 50 - Sin40)

Sin50 = cos (90-50) = cos 40 and similarly
Cos50 = sin 40
or
Sin50 - Cos40 = 0
Cos50 - Sin40 = 0

So Answer is ZERO