Question:
If the measure of arc CB is [tex]\frac{8}{3} \pi[/tex] units, what is the measure of ∠CAB?
Answer:
120°
Step-by-step explanation:
The figure has been attached to this response.
The figure shows a circle centered at A and has a radius of 4 units.
Also, the length of the arc CB (as given in the question) is [tex]\frac{8}{3} \pi[/tex] units.
The length L of an arc is given by;
L = [tex]\frac{\beta }{360} * 2\pi * r[/tex] -----------------(i)
Where;
β = angle subtended by the arc at the center of the circle and measured in degrees
r = radius of the circle
From the question;
β = ∠CAB
r = 4 units
L = [tex]\frac{8}{3} \pi[/tex]
Substitute these values into equation (i) as follows;
[tex]\frac{8}{3} \pi[/tex] = [tex]\frac{\beta }{360} * 2\pi * 4[/tex]
=> [tex]\frac{8}{3} \pi[/tex] = [tex]\frac{\beta }{360} * 8\pi[/tex]
Cancel 8[tex]\pi[/tex] on both sides
[tex]\frac{1}{3}[/tex] = [tex]\frac{\beta }{360}[/tex]
Cross multiply
3 x β = 360 x 1
3β = 360
Divide both sides by 3
[tex]\frac{3\beta }{3} = \frac{360}{3}[/tex]
β = 120°
Therefore, the measure of ∠CAB is 120°
