Answer:
x ≈ 12.7
Step-by-step explanation:
Since the base angles are congruent , both 45° then the triangle is isosceles with 2 congruent legs, both 9
Using Pythagoras' identity in the right triangle.
x² = 9² + 9² = 81 + 81 = 162 ( take square root of both sides )
x = ≈ 12.7 ( to the nearest tenth )