1. Cos 315° + Sin 135° = ?

Sudut Istimewa

1.

cos 315° + sin 135°

= cos (360° – 315°) + sin (180° – 45°)

= cos 45° + sin 45°

= 1/2 √2 + 1/2 √2

= √2

2.

tan 225° / sin 240°

= tan (180° + 45°) / sin (180° + 60°)

= tan 45° / (- sin 60°)

= -1/(1/2 √3

= – 2/3 √3

3.

tan 150° × cos 330°

= tan (180° – 30°) × cos (360° – 30°)

= – tan 30° × cos 30°

= – 1/√3 × 1/2 √3

= -1/2