Answer:
The number of distinct triangles that can be drawn using the dots = 6
Step-by-step explanation:
The parameters given are;
Two rows of three evenly spaced dots
To form a triangle, two dots will be selected from 1 row while the third dot will be selected from the other row
The number of ways of selecting the dots are therefore;
₃C₂ × ₃C₁ = 3 × 3 = 9 triangles
The same procedure can be done from the top row to give another 9 triangles
Which gives the total number of triangles = 18 triangles
The number of distinct triangles are found as follows;
Given that triangles obtained from the top row are similar to those of the bottom row, we reduce the range from which the distinct triangles can be found to 19 - 9 = 9 triangles
Of the 9 triangles formed by one dot on top and two dots on the bottom, the two adjacent dots of the three dots which are on the left and on the right of the lower row of dots, form the same three triangles with the three dots on the top row
Therefore, since there are 3 sets of two dots forming 9 triangles, each pair of dots can form 3 triangles, and as mentioned, 2 pairs of dots of the 3 pairs form the same triangles making the distinct triangle = 9 - 3 = 6.
