How To Find The Perimeter Of A Triangle With Vertices

Perimeter of a triangle

Given sides a, b, and c, finding the perimeter of a triangle is given past the following formula:

Showtime with a scalene triangle and characterization the sides as shown below.

Triangle with sides a, b, and c

P = a + b + c

Find the perimeter of a triangle when a = 3 cm, b = 5 cm, and c = 7

P = iii + 5 + vii = 15 cm

Find the perimeter when a = 4 cm, b = eight cm, and c = 12

P = 4 + eight + 12 = 24 cm

Find the perimeter when a = 1/ii cm, b = 3/2 cm, and c = 6/ii

P = 1/ii + 3/ii + half-dozen/2 = ( 1 + three + 6)/2 = 10/2 = 5 cm

If P = 30 cm and a = v and b = 7, what is c?

Using the formula P = a + b + c, supplant everything you know or everything given to y'all into the formula

Things that are given are P = 30, a = viii, and b = 10

Replacing them into the formula gives:

30 = 8 + 10 + c

30 = 18 + c

Yous end up with an add-on equation that you can solve to get c

However, some mental math should provide you with an answer besides.

Replace c by a question marking (?) and say to yourself the post-obit:

18 + ? = 30 or what tin I add to 18 to get 30 ? 18 + 12 = 30, so c = 12

If P = xx cm, b = seven and c = 8, what is a?

Using the formula P = a + b + c, supervene upon everything you lot know or everything given to you into the formula

Things that are given are P = 20, b = seven, and c = viii

Replacing them into the formula gives:

xx = a + 7 + 8

20 = a + xv

What tin I add together to fifteen to get 20? The answer is 5, so a = v

Source: https://www.basic-mathematics.com/perimeter-of-a-triangle.html