The three circles are congruent with radius . Line is tangent to the lower circle at point such that it is parallel to the line joining the centers of the above two circles. Line is a direct common tangent between the two circle shown in the figure.
If area of quadrilateral is . Then find integer nearest to
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Place the circles on a coordinate plane so that the center between the three circles is at (0, 0). Then the left circle has an equation of ( x + R ) 2 + ( y − 3 3 R ) 2 = R 2 , the right circle ( x − R ) 2 + ( y − 3 3 R ) 2 = R 2 , and the bottom circle x 2 + ( y + 3 2 3 R ) 2 = R 2 .
The y -coordinate of T can be found by solving 0 2 + ( T y + 3 2 3 R ) 2 = R 2 , which is T y = ( 1 − 3 2 3 ) R .
The x -coordinate of Q can be found by solving ( Q x − R ) 2 + ( T y − 3 3 R ) 2 = R 2 , which is Q x = ( 2 3 − 3 + 1 ) R
The x -coordinate of R is R x = R .
The y -coordinate of R can be found by solving R x 2 + ( R y + 3 2 3 R ) 2 = R 2 , which is R y = ( 3 3 − 1 ) R .
The height of the trapezoid is then h = T y − R y = ( 2 − 3 ) R .
The median of the trapezoid is then m = 2 1 ( 2 Q x + 2 R x ) = ( 2 3 − 3 + 2 ) R
The area of the trapezoid is A = ( 2 − 3 ) ( 2 3 − 3 + 2 ) R 2 = 1 0 , which solves to R 2 ≈ 1 3 . 9 1 9 ≈ 1 4 .