The distance from point D to E is 21 units. Point C is the midpoint, so CD is 10.5 units long (21/2 = 10.5)
We have a right triangle ACD. The legs are AC = 5 CD = 10.5 The hypotenuse is AD = x Because AD is another radius of the same circle
Use the pythagorean theorem to find x a^2 + b^2 = c^2 5^2 + 10.5^2 = x^2 25 + 110.25 = x^2 135.25 = x^2 x^2 = 135.25 x = sqrt(135.25) x = 11.629703349613 which rounds to 11.6 when rounding to the nearest tenth (one decimal place)
