Question

Ada yang bisa jelasin trigonometri 1 + tan^2 a = sec^2 a ?

Answer 1

1 + tan² a = sec² a
1 + sin² a/cos² a = sec² a
(cos² a + sin² a)/cos² a = sec² a
1/cos² a = sec² a
sec² a = sec² a (prove)

for your information:
sin² a + cos² a = 1
sec a = 1/cos a