Track / Stage 4 / 29 of 340 #289 of 1964

Problem 289

AMC 12 late, AIME early

Geometry Difficulty 4.5 Multiple choice

If the perimeter of the triangle shown is 21 , what is the value of $x$ ?

Pick one

Official solution

In terms of $x$ , the sum of the three side lengths of the triangle is $x+x+1+x-1=3 x$ . Since the perimeter is 21 , then $3 x=21$ and so $x=7$ .

ANsWER: (B)

Source: NuminaMath-1.5, licensed Apache-2.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.