Ikkilangan burchak va keltirish formulalari
Javoblar ota-onalar va o‘qituvchilar uchun.
1
sin α = 5/13, 0 < α < π/2 bo‘lsa, sin 2α ni toping.
120/169
2
cos α = 2/3 bo‘lsa, cos 2α ni toping.
−1/9
3
cos² (π/8) − sin² (π/8) ni hisoblang.
√2/2
4
sin 840° va tg 495° ni hisoblang.
sin 840° = sin 120° = √3/2; tg 495° = tg 135° = −1
5
sin(π − α) = sin α ni qo‘shish formulasi bilan isbotlang.
sin(π − α) = sin π cos α − cos π sin α = 0 · cos α − (−1) sin α = sin α.