Answer:
Step-by-step explanation:
Since it is a right-angled triangle, it has base, perpendicular and hypotenuse.
Base = r
Perpendicular = 14
Hypotenuse = r + 7
<u>Using Pythagoras theorem:</u>
Put the values
(r + 7)² = (r)² + (14)²
Using formula a² + 2ab + b² = (a + b)²
r² + 14r + 49 = r² + 196
<em>Subtract</em> r² to both sides
14r + 49 = 196
<em>Subtract</em> 49 to both sides
14r = 196 - 49
14r = 147
<em>Divide</em> 14 to both sides
r = 147 / 14
r = 10.5