Answer:
x = 5.7
Explanation:
Use the pythagorean theorem, which says a^2+b^2 = c^2 where c is the hypotenuse (longest side of a right triangle, always opposite the 90 degree right angle).
7^2 + x^2 = 9^2
49 + x^2 = 81
x^2 = 32
now take the square root of both sides
x = 5.65685424949
Round to the nearest tenth.
x = 5.7