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Old 07-27-2007   #4
bigcha
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1) The area of a trapezoid is found by taking the average of the two bases, top and bottom (called the midsegment) and multiplying by the height h: [(a + b) / 2] X h = Area ; so [(78 + b) / 2] X 36 = 3024 and b = 90 cm2) FAN is called a central angle (CA) and has the same measure in degrees of the arc above it. We find the measure of a sector by finding first the area of the entire circle, then multiplying by the fraction we want, which is the CA / 360 (central angle / entire circle)pi X 18^2) X (CA / 360) = 108 X pi so CA = 120 (degrees)3) These kind of area problems always need a plan, so here it is: find the area of the rectangle first, then subtract the area of the circles. I hope it's obvious that the width of the rectangle is the same as the diameter of the circle (14) and the length is two diameters (28). The radius of both circles is the same, 7. So: (area of rectangle) - (2 X area of circle) and (14 X 28) - (2 X [7^2 X pi]) = shaded region 392 - 98 pi or 84.28 using 3.14 for pi