Question

Find the are of the sector using radians. Show all work, including the conversion from degrees to radians.
**Open to see diagram**

Answer 1

one way to remember how to do this is notice
the area of the sector (with the central angle 100 degrees)
is part of the area of a whole circle.

Answer 2

do you know the area of a whole circle?

Answer 3

@phi nope...

Answer 4

it is famous
A= pi r^2
which means pi * r *r
where r is the radius
any idea what the area of your circle is ?

Answer 5

ohh that's what you meant.. then it'd be pi(100)^2

Answer 6

is the radius a length or an angle ?

Answer 7

oops i mean 4 pi

Answer 8

ok.

now we use this idea
if we made a sector that went "all the way round", it would have an angle of 360
(and its area would be the whole circle)
but if we go part way round, say 100 degrees
we would go 100/360 (a fraction) of the way round

Answer 9

in other words, the area of your sector is 100/360 of a whole circle

Answer 10

lost ?