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# Question on sector of a circle - pl help!!!! watch

1. "Let ABCD be a rectangle and CE an arc of the circle centred at A. If DA =4cm and AC = 8cm then what is the area of the shaded sector of the circle.
Attachment 725666
2. (Original post by cotton candie)
"Let ABCD be a rectangle and CE an arc of the circle centred at A. If DA =4cm and AC = 8cm then what is the area of the shaded sector of the circle.
Attachment 725654
it is not clear where E is.... the shaded part of your diagram does not look like a sector.
3. yes I agree we need the location of E to go ahead

4. the bit sticking out of the right of the rectangle looks like a segment, but the centre of the circle would be the middle of the rectangle, not A.
6. (Original post by cotton candie)
could you use the formula 1/2* r squared * theta where r is AC and theta is angleCAB?
you already know CA and AD, AD = BC , you can use trig to work out angleCAB
7. don't u want the region BCE?
8. AC= 8
BC=4
sin-1(4/8) = 30
angleCAB= 30
Area of sector = 1/2 * 8squared * pi/6 ( theta must be in radians)
area = 16/3 pi
9. (Original post by Brudor2000)
AC= 8
BC=4
sin-1(4/8) = 30
angleCAB= 30
Area of sector = 1/2 * 8squared * pi/6 ( theta must be in radians)
area = 16/3 pi
Thank u
10. (Original post by Brudor2000)
AC= 8
BC=4
sin-1(4/8) = 30
angleCAB= 30
Area of sector = 1/2 * 8squared * pi/6 ( theta must be in radians)
area = 16/3 pi
30/360 * pi * 8^2 = 16/3pi

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