Question

The perimeter of a certain pentagon is 14.8 centimeters. Four sides of this pentagon have the same length, in centimeters, h, and the other side has a length of 2.4 centimeters, as shown below. What is the value of h ?

Answer 1

i looked it up and got this

(The vertex formula is derived from the completing-the-square process, just as is the Quadratic Formula. ... For a given quadratic y = ax2 + bx + c, the vertex (h, k) is found by computing h = –b/2a, and then evaluating y at h to find k.

Answer 2

I think that h = 3.1

because I subtracted 2.4 from 14.8 and then divided 12.4 divided by 4 and I got 3.1

I am not certain that i am correct