Question

wysokosc stozka jest rowna 10 cm a tworzaca stanowi 260 % promienia podstawy . Oblicz pole powierzchni bocznej calkowitej bryly

Answer 1

H = 10cm
l = 260% * r = 2,6 * r = 2,6r

r^2 + h^2 = l^2 (tw. pit.)
r^2 + 10^2 = (2,6r)^2
r^2 + 100 = 6,76r^2
100 = 6,76r^2 - r^2
100 = 5,76r^2
r^2 = 100 / 5,76
r = 10 / 2,4
r = 100/24
r = 50/12 = 25/6
l = 2,6 * 25/6 = 26/10 * 25/6 = 65 / 6 

P = πr^2 + πrl = π * 625 / 36 + π * 25 / 6 * 65 / 6 = π * 625 / 36 + π * 1625 / 36 = π * 2250 / 36 = 250 / 4 π = 62,5π cm2