Question
How do I get (sinx cosy + cosx siny) (cosx cosy + sinx siny) in the form of 1/2(sin2x + sin2y)?
Answers
sinx cosy + cosx siny = sin(x+y)
cosx cosy + sinx siny = cos(x-y)
using the product-to-sum formulas,
sinA cosB = 1/2 (sin(A+B)+sin(A-B))
so, just plug in
A = x+y
B = x-y
cosx cosy + sinx siny = cos(x-y)
using the product-to-sum formulas,
sinA cosB = 1/2 (sin(A+B)+sin(A-B))
so, just plug in
A = x+y
B = x-y
Related Questions
sinx+ siny/ (cosx+cosy)= tan 1/2 (x+y)
prove this identity
please solve these if possible
Q1. If sinx +siny=3(cosy-cosx) then the value of sin3x/sin3y.
Q2...
cosx+cosy=a and sinx+siny=b show that sin2x+sin2y=2ab(1-(2/(a^2+b^2))
plz plz show step
2tan^-1(tanx/2×tan(π/4-y/2))=tan^-1(sinx×siny/cosx+cosy)