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Browse High School Triangles and Other Polygons
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Area of an irregular shape.
Classifying quadrilaterals.
Heron's formula.
Polygon diagonals.
Pythagorean theorem proofs.
Triangle congruence.
 What Is the Length of PR? [01/01/2003]

In a circle of radius 6, a triangle PQR is drawn having QR=8 and
PQ=10.
 Why are Manhole Covers Round? [05/09/2000]

Why are most manhole covers round? Why aren't manhole covers on the
streets squares or rectangles?
 Why a Square Maximizes Area/Perimeter [07/24/2002]

Is it possible to make a rectangle with a perimeter of 16 feet and an
area greater than 16 square feet?
 Why Do the Angles of a Triangle Add to 180 Degrees? [4/17/1996]

We were wondering why all the angles in a triangle add up to 180 degrees.
 Why do the Midpoints of Quadrilaterals Make a Parallelogram? [2/7/1996]

Why is it that if you join the midpoints of any quadrilateral you always
get a parallelogram?
 Why There Is No SSA Congruence Postulate or Theorem [03/29/2005]

In the correspondence of two triangles, if SSA = SSA, are the
triangles congruent?
 Will the Tree Hit the House? [05/18/1999]

A tree is leaning at 70 degrees, our house is 66 1/2 feet away, and the
angle from our house to the top of the tree is 40 degrees...
 World War II Window Blackout [10/21/2001]

Mr. Brown had a square window 120cm x 120cm, but the only material he
could find was a sheet of plywood 160cm x 90cm; same area, different
shape. He drew some lines and cut out just two congruent shapes, which he
joined to make a square of the correct size. How did he do it?
 You Can't Trisect an Angle [7/16/1996]

Who proved you can't trisect an angle?
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