# Use sine ratio to calculate angles and side (Sin = $\frac{o}{h}$ )

### Use sine ratio to calculate angles and side (Sin = $\frac{o}{h}$ )

One of the trigonometric ratios is sine ratio. It is the opposite side over the hypotenuse of right triangles. In other words, we can find the angles and sides of right-angled triangles by using the sine ratios.

#### Lessons

• 1.
What are sine, cosine and tangent?

• 2.
Determine each sine ratio using calculator
a)
$\sin 60^\circ$

b)
$\sin-60^\circ$

• 3.
Determine the angle to the nearest degree
a)
$\sin \theta =0.57$

b)
$\sin \theta = -0.65$

• 4.
Determine the angles and sides using Sine ratio
a)
Find angle A and B:

b)
Find the value of "x" using sine

c)
Find the value of "x" using sine

• 5.
Draw and label a right triangle to illustrate sine ratio, then calculate the angle.
a)
$\sin \theta = {5 \over 13}$