I am really not sure why please help

An isosceles triangle has two equal sides (or three, technically) and two equal angles (or three, technically). The equal sides are called legs, and the third side is the base. ... The angle between the two legs is called the vertex angle. :))

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2