What is the sum of n natural numbers: 1+2++n?

S = 1/2 n (n+1)

Step-by-step explanation:

1 + 2 + 3 + ... + n

Now write in reverse order:

n + n-1 + n-2 + ... + 1

Add together:

n+1 + n+1 + n+1 + ... + n+1

n (n+1)

Since this is double the sum:

S = 1/2 n (n+1)

step-by-step explanation:

use pothagarean therom

a^2+b^2=c^2 so first ac

acm is a right triangle because c= 90°

and am (the hypotenuse or c) =16+9 =25

but there is not enough info we need another angle or side length

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