document.write( "Question 1182794: Two circles, one of radius 1 and the other of radius 2, touch externally at P.
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document.write( "A straight line through P cuts the area formed by these two circles in the ratio 1:2.
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document.write( "In what ratio does this line cut the area of the smaller circle? \n" );
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Algebra.Com's Answer #812875 by greenestamps(13200)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Here is a sketch of the two circles and the line through their point of tangency: \n" ); document.write( " \n" ); document.write( "The figures of the small circle with its chord and of the large circle and its chord are similar figures. \n" ); document.write( "The radius of the small circle is 1; the radius of the large circle is 2. So the areas of the two circles are pi and 4pi. \n" ); document.write( "Let x be the area of the smaller portion of the small circle; then the area of the larger portion is (pi-x). \n" ); document.write( "Since the scale factor between the two circles is 1:2, the ratio of corresponding area measurements between the two circles is 1:4. So the smaller portion of the large circle is 4x, and the larger portion of the large circle is 4(pi-x) = (4pi-4x). \n" ); document.write( "We are told that the line divides the total area of the two circles in the ratio 1:2. The total area is 5pi. That means the area of the smaller portion of the small circle, plus the larger portion of the area of the large circle, is 2/3 of the total 5pi: \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "The area of the smaller portion of the small circle is x=(2/9)pi; that means the area of the larger portion of the small circle is (pi-x) = (7/9)pi. \n" ); document.write( "And that means the smaller circle is divided in the ratio (2/9):(7/9) = 2:7 \n" ); document.write( "ANSWER: 2:7 \n" ); document.write( " \n" ); document.write( " |