Geom027: Make the largest area using 4 cardboards

Geom027:   Make the largest area using 4 cardboards
There are 4 cardboards, two of them are 2 inches by 13 inches, and the other two are 3 inches by 4 inches. How can you use these 4 cardboards (without cutting and bending) to make a surrounded area, which is the largest area you can get?

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Posted in: Geometry

Geom026: Which triangle has the largest perimeter?

Geom026:   Which triangle has the largest perimeter?
  By choosing a particular point C from the chord AB, a triangle can be formed by connecting points A, B and C. There can be unlimited points like C on chord AB. In the figure, we just show you 3 of them. However, which triangle can have the largest perimeter?

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Posted in: Geometry

Geom025: How big is quadrilateral DBEF?

Geom025:   How big is quadrilateral DBEF?
  ABC is a general triangle and its area is equal to 132 cm square

The opposite side of edge A is divided in 4 equal parts and the opposite side of edge C in 3 equal parts

Straight lines join the point A to each quarter of line BC. Likewise, from point B to each third of line AB.

How big is the area of quadrilateral DBEF?

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Posted in: Geometry

Geom024: A special triangle

Geom024:   A special triangle
  Imagine a special triangle. The height and the three sides of this triangle are 4 consecutive integers. The example shown here is not quite the correct answer because the closest integers we can get are 3, 3, 4, 5 or 2.4, 3, 4, 5. Can you figure out what this triangle is?

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Posted in: Geometry

Geom023: Cut into 4 pieces to form a square

Geom023:   Cut into 4 pieces to form a square
  Cut the figure into 4 pieces to form a new square with 29 units. You do not need to cut along either dashed lines or solid lines.

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Posted in: Geometry

Geom022: Cut into 2 peices to form a square

Geom022:   Cut into 2 peices to form a square
Cut the figure along the dashed line or solid line into 2 pieces to form a new square which has 16 units. 

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Posted in: Geometry

Geom021: How many degrees is the total of all the sharp angles?

Geom021:   How many degrees is the total of all the sharp angles?
  There are 5 sharp angles in a star. How many degrees is the total of all 5 sharp angles?

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Posted in: Geometry