bantuin dong kakak abang ngerjain nya

Trigonometri
1. sin 353 = sin (360 - 7) = - sin 7

2. cos 115 = cos (180-65) = - cos 65

3. sin² (780) = (sin 780)² = { sin (2x360 +60)}²
sin² 780 = (sin 60)² = (1/2 √3)² = 3/4

4. cos² 510 = (cos 510)² = {cos (360 + 150)² = (cos 150)²
cos² 510 = (cos (180 - 30))² = (- 1/2 √3)² = 3/4

5. sin B = 2/3
cos B = √(1- sin²²= B) = √(1 - 4/9) = √(5/9) = 1/3 √5

cot (270-B)=  tan B = sin B/cos B = (2/3) / (1/3 √5)  = 2/√5 = 2/5 √5