Question

Sin 120° ,sin 240° ,sin 270°, find the value

Answer 1

Answer:

NOTE :-

• Sin 0° = 0 = Cos 90°
• Sin 30° = 1/2 = Cos 60°
• Sin 45° = 1/√2 = Cos 45°
• Sin 60° = √3/2 = Cos 30°
• Sin 90° = 1 = Cos 0°

ALSO NOTE :-

• Sin (90-a) = Cos a
• Sin (90+a) = Cos a
• Sin (180-a) = Sin a
• Sin (180+a) = -Sin a
• Sin (270-a) = - Cos a
• Sin (270+a) = - Cos a
• Sin (360-a) = - Sin a
• Sin (360+a) = Sin a

REQUIRED VALUES :-

• Sin (120°) = Sin(90° + 30°) = Cos 30° = √3/2
• Sin (240°) = Sin(270° - 30°) = -Cos 30° = -√3/2
• Sin (270°) = Sin(270° + 0°) = -Cos 0° = -1

Answer 2

Answer:

We know that the value of cos 30 degrees is √3/2. Therefore, sin 120° = √3/2.