What is the length of arc ABC in terms of pi?

Question

anonymous · Answer

attachment

anonymous · Answer

choices are:
a 15pi cm
b 3.75pi cm
c 7.5pi cm
d 15pi cm

directrix · Answer

c 7.5pi cm

anonymous · Answer

got it! thanx

anonymous · Answer

length=n degree/ 360 degree*(2.pi.r)

paxpolaris · Answer

$$\Large{45 \over 360 } ={ x \over circumference}$$

anonymous · Answer

The circumference of the whole circle is 2 pi r, so don't calculate the pi and divide it by 8 because 45 degrees is 1/8 of the circle. The answer will be in terms of:
 pi cm.

directrix · Answer

You can work out a proportion with 45/360 = Arc/ Circumference

1/8 = A / 60 pi

Arc length = (15/2) pi = 7.5 pi

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If you see that 45 degrees is 1/8 of the 360 degrees "in" a circle, then the 45 degrees converted to arc length for this particular circle will be 1/8 of its circumference. The circumference is 2 pi r which is 60 pi.

This type problem always reminds me of changing money from one currency unit to that of another.