Use the distance formula to find 2 sides. O through A and O through B. distance formula is in the image. OA root[(x2-x1)^2+(y2-y1)^2] root[(4-0)^2+(0-0)^2] root[16] 4 OB root[(x2-x1)^2+(y2-y1)^2] root[(0-6)^2+(6-0)^2] root[36+36] root[72] 6root[2] multiply the two numbers and divide by 2. 4 * 6root[2] 24root[2] 24root[2]/2 12root[2]