A triangle is formed by natural numbers from 1 to 21. First row has 1st…
2018
A triangle is formed by natural numbers from 1 to 21. First row has 1st number, 2nd row has next two numbers, 3rd row has next three numbers and so on. Which of these numbers when joined forms a triangle?
- A.
5, 12, 14, 5
- B.
1, 7, 16, 1
- C.
9, 13, 18, 9
- D.
11, 13, 15, 11
Attempted by 1 students.
Show answer & explanation
Correct answer: A
The numbers from 1 to 21 are arranged in a triangular pattern as follows:
Row 1: 1
Row 2: 2, 3
Row 3: 4, 5, 6
Row 4: 7, 8, 9, 10
Row 5: 11, 12, 13, 14, 15
Row 6: 16, 17, 18, 19, 20, 21
A triangle is formed when three numbers occupy the three vertices of a triangular cell in this arrangement. Such a triangle consists of two adjacent numbers in one row and the number directly above or below them in the neighboring row.