Question

100=21y^2 ?

Answer 1

Divide both sides by 21.
100/21=y^2
Take the square root.
y=sqrt(100/21)

Answer 2

but that is like 2.81 ?

Answer 3

It doesn't have to be a whole number :)

Answer 4

It will be 2.18 when rounded off to 2 decimal places

Answer 5

well i know that but its one of those circle problems with half the angle in and half out...its confusing. haha

Answer 6

If you're being precise don't forget the negative square root, i.e. -2.18

Answer 7

that's the problem.