x² = 6² - 4²
x² = 36 - 16
x² = 20
x = √20 = 2√5
P = ½ * 6 * 2√5 = 3 * 2√5 = 6√5
Ob = 4 + 6 + 2√5 = 10 + 2√5 = 2(5 + √5)
