∵ pd = radius = 7 ⇒⇒⇒ ∴ ad = 2 * radius = 2 * 7 = 14 ∵ ae = 4 ⇒⇒⇒ ∴ ed = ad - ae = 14 - 4 = 10 ∵ ad is a diameter Δ acd is a triangle drawn in a half circle ∴ Δ acd is a right triangle at c ∵ bc ⊥ ad at point e By applying euclid's theorem inside Δ acd ∴ ce² = ae * ed ∴ ce² = 4 * 10 = 40 ∴ ce = √40 = 2√10 ≈ 6.325
