The perimeter of a triangle is 31 cm. Sides #1 and #2 have equal lengths, while Side #3 is one centimeter shorter than twice the length of Side #1.

Let’s determine how long each side is:

a) Let x represent the length of Side #1. What essential part of this “let” statement is missing?

x = 7

All 8 angles measure 135°

Step-by-step explanation:

(n-2)·180 = (8-2)·180 = 1,080°; this is the total of all interior angles

each angle is equal so we can divide 1080 by 8 and find that each angle measures 135°

to solve for 'x':

16x + 23 = 135

16x = 112

x = 112/16

x = 7

check:  16(7) + 23 = 135

             112 + 23 = 135

             135 = 135