`If x cos alpha + y sin alpha = x cos beta + y sin beta "then"`
`"tan" (alpha + beta)/2=`

If x cos alpha + y sin alpha = x cos beta + y sin beta "then" (2(1-cos (alpha - beta)))/(cos beta - cos alpha)^(2)=

If x cos alpha + y sin alpha = x cos beta + y sin beta = 2a then cos alpha cos beta =

If x cos alpha + y sin alpha=x cos beta+y sin beta,"show that",y=x "tan"(alpha+beta)/2

If x cos alpha + y sin alpha = x cos beta + y sin beta "then" (sin alpha - cos alpha - sin beta + cos beta)/(sin alpha + cos alpha - sin beta - cos beta)=

If x cos alpha + y sin alpha = x cos beta + y sin beta = a, 0

If x=cos alpha+i sin alpha, y=cos beta+i sin beta then " (y)/(x)-(x)/(y)=

If x= cos alpha+ i sin alpha, y = cos beta+ i sin beta, then prove that (x-y)/(x+y) =i (tan )(alpha-beta)/2

(cos alpha-cos beta) / (sin beta-sin alpha) = tan ((alpha + beta) / (2))