Question

calculate the angle marked with small letters​

Answer 1

Step-by-step explanation:

Example

Find the nth term of the sequence: 2, 6, 12, 20, 30...

n = 1 2 3 4 5

n(n + 1)/2 = 1 3 6 10 15

Clearly the required sequence is double the one we have found the nth term for, therefore the nth term of the required sequence is 2n(n+1)/2 = n(n + 1).

The Fibonacci sequence

The Fibonacci sequence is an important sequence which is as follows: 1, 1, 2, 3, 5, 8, 13, 21, ... . The next term of this well-known sequence is found by adding together the two previous terms.

Answer 2

nice question actually nice