Question

Допоможііітьь!
Обчислити:
A) sin135°+cos120°
Б) 5sin30°+ctg135°

Answer 1

Ответ:

a

$\sin(135^{\circ} ) + \cos(120^{\circ} ) = \sin(180 ^{\circ} - 45^{\circ} ) + \cos(180^{\circ} - 60^{\circ} ) = \\ = \sin(45^{\circ} ) - \cos(60^{\circ} ) = \frac{ \sqrt{2} }{2} - \frac{1}{2}$

б

$5 \sin(30^{\circ} ) + ctg(135^{\circ} ) = 5 \sin(30^{\circ} ) - ctg(45^{\circ} ) = \\ = 5 \times \frac{1}{2} - 1 = 2.5 - 1 = 1.5$