Question

Can someone help me with this? sin150° =

Answer 1

`\sin(150 \degree) = (1)/(2)`

EXPLANATION

The principal angle for 150° is 30°.

The terminal side of 150° is in the second quadrant.

In this quadrant the sine ratio is positive.

This implies that;

`\sin(150 \degree)= \sin(30 \degree)`

On the unit circle,

`\sin(30 \degree) = ( 1 )/(2)`

Therefore

`\sin(150 \degree)= \sin(30 \degree) = (1 )/(2)`

Answer 2

sin(150°) = 1/2

Explanation:

* Lets study how we can solve this problem

- At first the measure of the angle is 150°

- Ask your self in which quadrant can you find this measure

* To know the answer lets revise the four quadrants

# First quadrant the measure of all angles is between 0° and 90°

the measure of any angle is α

∴ All the angles are acute

∴ All the trigonometry functions of α are positive

# Second quadrant the measure of all angles is between 90° and 180°

the measure of any angle is 180° - α

∴ All the angles are obtuse

∴ The value of sin(180° - α) only is positive ⇒ sin(180° - α) = sinα

# Third quadrant the measure of all angles is between 180° and 270°

the measure of any angle is 180° + α

∴ All the angles are reflex

∴ The value of tan(180° + α) only is positive ⇒ tan(180° + α) = tanα

# Fourth quadrant the measure of all angles is between 270° and 360°

the measure of any angle is 360° - α

∴ All the angles are reflex

∴ The value of cos(360° - α) only is positive ⇒ cos(360° - α) = cosα

* Now lets check the angle of measure 150

- It is an obtuse angle

∴ It is in the second quadrant

∴ the value of sin(150) is positive

∴ sin(150°) = sinα

∵ 180 - α = 150 ⇒ isolate α

∵ α = 180° - 150° = 30°

∴ sin(150°) = sin(30°)

∵ sin(30°) = 1/2

∴ sin(150°) = 1/2