You can put this solution on YOUR website! If one angle is 45 deg the other will also be 45deg in a right triangle.
sum of all angles of triangle = 180 deg.
The legs will be x each.
hypotenuse = 7
x^2+x^2=7^2 by pythagoras theorem
2x^2=49
x^2=49/2
x= 7/sqrt(2)