tolong yaa pleeaseee kita sudah berjuang

jawab

(1)
cos 72 + sin72 tan 36  = 1
cos 72 + sin 72 tan 36 =
= cos 72 + sin 72 . sin 36/cos 36
= (cos 72 cos 36 + sin 72 sin 36)/cos 36
= cos (72 - 36) / cos 36
= cos 36/cos 36
= 1

(2)
m =  p tan α
n = p tan 2α
n = 2p tan α/(1 - tan² α)

(2m/n ) = 2 p tan α (1- tan² α)/(2p tan α)
(2m/n ) = 1 - tan² α

(2m/n- 1) p² +m² = 0
(2m/n -1) p²  + m² =
= (1 - tan² α - 1) p² + (p tan α) ²
= - p² tan² α + p² tan² α
= 0