Answer:
r = 10.5
Step-by-step explanation:
using the Pythagorean theorem:
(7 + r)² = 14² + r²
49 + 14r + r² = 196 + r²
subtract r² from both sides of the equation:
14r + 49 = 196
subtract 49 from both sides:
14r = 147
divide both sides by 14:
r = 10.5
