The question is an illustration of an equilateral triangle.
From the complete question, the complete side of the triangle contains the following numbers:
1, 6 and 2.
The sum of these numbers represent the side length
[tex]Length = 1 + 6 + 2[/tex]
[tex]Length = 9[/tex]
On the base of the triangle, the numbers are 1 and 3.
So, the number that completes these set of numbers is 5.
This is so because, 5 added to the sum of 1 and 3 is 9
Lastly, the numbers on the last side of the triangle are 2 and 3.
So, the number that completes these set is 4.
This is so because, 4 added to the sum of 2 and 3 is 9
See attachment for the complete diagram
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