Machine-translated by Google. Questions are authored in English.
Top

Discussion

How many triangles are there in the given figure ?

(The figure is a rectangle divided by a vertical line into two squares, with both diagonals drawn in each square and a horizontal line drawn across the whole rectangle through the two points where the diagonals cross.)

  • A.10
  • B.12
  • C.18
  • D.28

Answer: D

There are 28 triangles in the figure.

Take each square as 2 units wide, so the whole figure is 4 by 2. Count by size:

TriangleCount
Smallest: halves of the left and right quarters of each square, cut by the horizontal line8
Top and bottom quarters of each square4
Whole left and right quarters of each square4
Triangles across the middle line, on the horizontal line with apex at the top or bottom middle2
Half-squares cut off by one diagonal8
Large triangles with the whole long side as base and apex at the middle of the opposite side2

\[ 8 + 4 + 4 + 2 + 8 + 2 = 28 \]

Counting only the small pieces gives 12, and missing the triangles that span both squares gives 18 or less.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.