Question

if tanA+secA=x/y then prove that, cosA=2xy/x^2+y^2
​

Answer 1

Answer:

secA + tanA = x/y

rewrite each as function of only sine and cosine

1/cosA + sinA / cosA = x/y

1 + sinA x

----------- = ------

cosA y

so cosA = y

Answer 2

Answer:

cosA-sin square A upon 1-tan A cosA - sin A