Answer:
x = 3√5
Explanation:
we can use the Pythagorean Theorem twice, first to find the longer leg of the left triangle:
7² + b² = 10²
b² = 100-49
b² = 51
b = √51 which we can simplify to be √9·√3·√3 = 3·3 = 9
we can use the Pythagorean Theorem next to find 'x':
x² + 6² = 9²
x² + 36 = 81
x² = 45
x = √45 = √9·√5 or 3√5