2014/04/22

157. Circles in a triangle

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In the diagram, a circle is inscribed in an equilateral triangle.  A smaller circle is inscribed in the space between the first circle and the triangle.
⒜  Determine the ratio of the area of the larger circle to the area of the smaller circle.
⒝* Determine the ratio of the area of the light blue region to the area of the pink region.

2014/04/20

156. Weighted averages exercise


A mathematics test with 18 boys, 22 girls.  If the class average=70.7 and the boys' average=68.5, determine the girls' average.

(from Twitter)

2014/04/15

155. Three angle sum

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In the diagram, one side of a rectangle is divided into three equal parts.
Determine the sum of angles x, y and z.