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For a square of side a, the area is simple: a2. The perimeter is 4a. How do you deal with a circle, of diameter a? It's obviously less than a2. It turns out to be pi/4 times a2. Or pi times radius squared where pi has been worked out to be 3.1415..... As for angle, for lots of applications it appears a good way of measuring angle by using the length of a piece of circumference of a circle divided by the radius. The units for this is radians. A length of circumference equal to the circle radius gives an angle of 1 in these units when you draw straight lines from the ends of this bit of circumference to the centre. So the whole way around the circle (360o) then is 2.pi.r divided br r, radians, which is just 2 pi radians.
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Area of a part of circle?
Area of a sector of a circle = (pi) x (radius)2 x (central angle of the sector / 360)
What is the area of a sector of a circle with central angle is 18.0 and radius is 5 inches?
The area of the whole circle is pi*r2 = 25*pi To go any further, you need to assume that the central angle is given in degrees. If the sector is 18.0 degrees out of a circle of 360 degrees so the sector represents 18/360 = 1/20 of the whole circle. The area of the sector, therefore, is 1/20 of the area of the whole circle = 25*pi/20 = 5*pi/4 or 1.25*pi = 12.566 sq inches.
The area of the sector formed by the 110 degree central angle is 40 units squared What is the radius of the circle?
measure of central angle/360 degrees = area of sector/area of circle 110 degrees/360 degrees = 40 unit2/ pi r2 unit2 11/36 = 40/pi r2 11 pi r2 = 40 x 36 11 pi r2 = 1,440 r2 = 1,440/11 pi r = square root of 1,440/11 pi r = 20.3 unit approximately
How would you convert an angle in degrees to angle in radians?
Divide the angle measured in degrees by (180/pi). Alternatively, multiply by (pi/180).
Surface area of elbow?
The formula for the surface area of an elbow (or 90° angle) is (pi^2 * (radius2^2 - radius1^2) ) / 4. Where pi = 3.14159, radius 2 = the radius from the center to the outside, and radius 1 = the radius from the center to the inside.
