SOLUTION: A*sin(X)+B*sin(X+U)=C*sin(X+W), with C=sqrt(A^2+B^2+2*A*B*cos(U)) and tan(W)=(B*sin(U))/(A+B*cos(U)). What are the intermediate steps leading to this result?

Algebra ->  Trigonometry-basics -> SOLUTION: A*sin(X)+B*sin(X+U)=C*sin(X+W), with C=sqrt(A^2+B^2+2*A*B*cos(U)) and tan(W)=(B*sin(U))/(A+B*cos(U)). What are the intermediate steps leading to this result?      Log On


   



Question 1087083: A*sin(X)+B*sin(X+U)=C*sin(X+W), with C=sqrt(A^2+B^2+2*A*B*cos(U))
and tan(W)=(B*sin(U))/(A+B*cos(U)).
What are the intermediate steps leading to this result?

Answer by Edwin McCravy(20086) About Me  (Show Source):
You can put this solution on YOUR website!
A*sin(X)+B*sin(X+U)=C*sin(X+W), with C=sqrt(A^2+B^2+2*A*B*cos(U))
and tan(W)=(B*sin(U))/(A+B*cos(U)).
We are given that  tan(W)=(B*sin(U))/(A+B*cos(U)).

Since TANGENT=OPPOSITE%2FADJACENT and

tan%5E%22%22%28W%29=%28B%2Asin%5E%22%22%28U%29%29%2F%28A%2BB%2Acos%5E%22%22%28U%29%29,

we can draw a right triangle with B*sin(U) as the
opposite side of angle W and A+B*cos(U) as the
adjacent side of W:

 

We calculate the hypotenuse:

HYPOTENUSE%5E2%22%22=%22%22ADJACENT%5E2%2BOPPOSITE%5E2

HYPOTENUSE%5E2%22%22=%22%22%28A%2BB%2Acos%5E%22%22%28U%29%5E%22%22%29%5E2%2B%28B%2Asin%5E%22%22%28U%29%5E%22%22%29%5E2

HYPOTENUSE%5E2%22%22=%22%22A%5E2%2B2AB%2Acos%5E%22%22%28U%29%2BB%5E2%2Acos%5E2%28U%29%2BB%5E2%2Asin%5E2%28U%29

HYPOTENUSE%5E2%22%22=%22%22A%5E2%2B2AB%2Acos%5E%22%22%28U%29%2BB%5E2%28cos%5E2%28U%29%5E%22%22%2Bsin%5E2%28U%29%29

HYPOTENUSE%5E2%22%22=%22%22A%5E2%2B2AB%2Acos%5E%22%22%28U%29%2BB%5E2%281%5E%22%22%5E%22%22%29

HYPOTENUSE%5E2%22%22=%22%22A%5E2%2B2AB%2Acos%5E%22%22%28U%29%2BB%5E2

HYPOTENUSE%22%22=%22%22sqrt%28A%5E2%2B2AB%2Acos%5E%22%22%28U%29%2BB%5E2%29

Notice that this result is the exact value that was given for C. So

HYPOTENUSE%22%22=%22%22C



Let's start with right side of what we have to prove:

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22
C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

Since COSINE=ADJACENT%2FHYPOTENUSE and SINE=OPPOSITE%2FHYPOTENUSE,
we use the right triangle above to substitute for cos(W) and sin(W)

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22

C%2Asin%5E%22%22%28X%2BW%29%22%22=%22%22A%2Asin%5E%22%22%28X%29%2BB%2Acos%5E%22%22%28X%2BU%29%5E%22%22

Edwin