The first five triangular numbers are shown, wheren represents the number of dots in the base of the figure, and d(n) represents the total number of dots in the figure. 0(1) 000(3) 000000(6) 0000000000(10) 000000000000000(15)

When n=1, there is 1 dot. When n=2, there are 3 dots. When n = 3, there are 6 dots. Notice that the total number of dots d(n.) increases by n each time.
Use induction to prove that d (n) n()

Part A
Prove the statement is true for n=1
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