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# Find the perimeter of the triangle?

Really need help with this! Thanks.

### 2 Answers

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- RRLv 54 weeks ago
You can find two of the sides by counting the squares: 7 and 5.

You can find the third side using Pythagoras:

7² + 5² = h²

49 + 25 = h²

74 = h²

h = 8.6

P = 8.6 + 7 + 5

P = 20.6

- AlanLv 74 weeks ago
Use the distance formula for each side .

distance between points (x_1, y_1) and (x_2, y_2) =

sqrt ( (y_2 -y_1)^2 + (x_2-x_1)^2 )

then add them all up.

1st side goes from (2,1) to (2,8)

distance side 1 = sqrt( (2-2)^2 + (8-1)^2 ) = 7

2nd side goes from (2,1) to (7,1)

distance side 2 = sqrt( (7-2)^2 + (1-1)^2 ) = 5

side 3 goes from (2,8) to (7,1)

distance side 3 = sqrt ( (7-2)^2 + (8-1)^2 ) =

= sqrt( 25 + 49) = sqrt( 74)

perimeter = 5 + 7 + sqrt(74)

perimeter = 20.60232527

so the answer is (B)

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