Tag Archives: geometry

Area of Trapezoid

In a trapezoid with parallel to , the diagonals intersect at point . The area of triangle is , and the area of triangle is . Find the area of the trapezoid. Source: NCTM Mathematics Teacher, August 2006 Solution Draw … Continue reading

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Tangent Circles

Consider the circles that have radii and are tangent to the line at the point . Find the sum of the coordinates of the centers of the circles. Source: NCTM Mathematics Teacher, August 2006 Solution For the two circles to … Continue reading

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Round Table

A round table can be made square by dropping the four leaves. If a side of a square table measures inches, to the nearest hundredth of a square inch, how much smaller is the area of the table when the … Continue reading

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Largest Equilateral Triangle in a Square

How long is the side of the largest equilateral triangle that can be inscribed in a square with side length ? Source: NCTM Mathematics Teacher, August 2006 Solution A first guess is an equilateral triangle of side length . Could … Continue reading

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Equilateral Triangle and Square

A pentagon made up of equilateral triangle with side length on top of square is inside a circle passing through points , and . Find the radius of the circle. Source: NCTM Mathematics Teacher, August 2006 Solution Let be the … Continue reading

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Making Triangles

You have six sticks of lengths , and cm. Find the number of noncongruent triangles that can be formed using three of these sticks as sides. Source: NCTM Mathematics Teacher, August 2006 Solution Three sticks make a triangle. There are … Continue reading

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Two Equilateral Triangles

If two equilateral triangles of area intersect to form a regular hexagon, then what is the area of the hexagon? Source: NCTM Mathematics Teacher, September 2006 Solution If we subdivide an equilateral triangle into smaller congruent equilateral triangles as shown … Continue reading

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Two Squares

If the vertices of square are the midpoints of the edges of square , then what is the ratio of the area of square to square ? Source: NCTM Mathematics Teacher, September 2006 Solution The diagonal of square divides square … Continue reading

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Maximum Angle

The measures of five angles of a convex polygon are each equal to . In which of the five open intervals does the maximum angle of all such polygon lie? (a) (b) (c) (d) (e) Source: NCTM Mathematics Teacher, September … Continue reading

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Length of Hypotenuse

Consider the line containing the points and . What is the length of the hypotenuse of the right triangle formed by the intersections of and the -and -axes? Source: NCTM Mathematics Teacher, September 2006 Solution Points , and are the … Continue reading

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