Tolong ya nomor 1 sama 2 pake caranya

1) cos a = 3/5
sisi depan 3
sisi miring 5
sisi samping 4
sin a = 4/5
tan a = 4/3
sin a . tan a - 1 / 2.tan²a
= (4/5).(4/3) - 1 / 2(4/3)²
= (16/15 - 15/15) / 2(16/9)
= 1/15 / 32/9
= 1/15 × 9/32
= 3/160

2) tan a = 1/√7
sisi depan 1
sisi samping √7
sisi miring √8
cosec²a = (√8/1)² = 8
secan²a = (√8/√7)² = 8/7

= (8 - 8/7) / (8+8/7)
= (56/7 - 8/7) / (56/7 - 8/7)
= (48/7) / (64/7)
= 48/64
= 6/8
= 3/4