X^2 + 12 =3 solve, give exact solution(s) no rounding or decimals

Moira has a canvas that is 8 inches by 10 inches. she wants to paint a line diagonally from the top left corner to the bottom right corner. approximately how long will the diagonal line be?

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

The midpoints of the sides of the large square are joined to form a smaller square. what is the area of the smaller square