document.write( "Question 1182637: A rectangular lot 80 m x 40 m long is divided into two
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document.write( "areas by an arc whose center is at the mid-point of the
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document.write( "shorter side. If the radius of the arc is 30 m, what is the
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document.write( "ratio of the area of the smaller part to the area of the
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document.write( "bigger part? \n" );
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Algebra.Com's Answer #812743 by greenestamps(13200)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Here is a sketch.... \n" ); document.write( " \n" ); document.write( "Rectangle ABCD has side lengths 40 and 80; the circular arc is centered at E, the midpoint of AB. AE=20 and EG=30; the Pythagorean Theorem gives us AG=10*sqrt(5). \n" ); document.write( "The area of the smaller portion of the lot is the area of the two congruent triangular regions EAG and EBF, plus the area of the circle sector EFG. \n" ); document.write( "The areas of the triangles are easy to calculate. \n" ); document.write( "For the area of the circle sector, you need to find what fraction of a circle the sector is, so you need to find the measure of angle FEG. Angle FEG is twice angle AGE; angle AGE is arcsin(20/30). Then the area of the sector is that fraction, times the area of the whole circle, which is (pi)r^2 = 900pi. \n" ); document.write( "I leave it to you to do the calculations.... \n" ); document.write( "To check your calculations, here are my figures, slightly rounded: \n" ); document.write( "Angle FEG: 83.62 degrees \n" ); document.write( "Area of circle sector: 656.76 m^2 \n" ); document.write( "Area of smaller portion of lot (circle sector plus two triangles): 1103.97 m^2 \n" ); document.write( "Area of larger portion: 3200-1103.97 = 2096.03 m^2 \n" ); document.write( "Ratio of smaller to larger: 1104:2096 \n" ); document.write( " \n" ); document.write( " |