Question

If sinA= 5/13 in quadrant 1, find sin A/2?

having trouble with double and half angle formulas

Answer 1

Given `sinA=5/13" where "A in "Quadrant1"`

So `cosA=sqrt(1-sin^2A)=sqrt(1-25/169)=12/13`

So `1-2sin^2(A/2)=12/13`

`=>2sin^2(A/2)=1-12/13=1/13`

`=>sin(A/2)=1/sqrt26`

Negative value rejected as `Ain"Quadrant1"`