Question

What is the value of cos240

Answer 1

Step-by-step explanation:

The value of( cos240°) is,

-0.5

Answer 2

Answer:

- 0.5

Step-by-step explanation:

From the properties of trigonometric ratios :

• cos( 360 + A ) =  cosA          { Since cose of any angle is periodic to 2π or 360° }
• cos( 90° - A ) = sinA
• sin30° = 1 / 2

⇒ cos( 240° )

⇒ cos( 360° - 120° )

⇒ cos( - 120° )

⇒ cos( 120° )             { cos( - x ) = cox }

⇒ cos( 90° - ( - 30° ) )

⇒ sin( - 30° )

⇒ - sin30°

⇒ - 1 / 2

⇒ - 0.5