The length of one side of the triangle is 0.35 of the perimeter and the length of the other side is 45%

| March 1, 2021 | education

The length of one side of the triangle is 0.35 of the perimeter and the length of the other side is 45% of the perimeter, the length of the third side is 8.4 cm. Find the perimeter of the triangle.

Method I.

Let p be the perimeter of the triangle.

The first side is 0.35 perimeter, it is equal to 0.35 rubles.

The second side is 45% of the perimeter (45% = 0.45), it is equal to 0.45r.

The perimeter is the sum of the lengths of all sides:

p = 0.35p + 0.45p + 8.4.

p = 0.8p + 8.4.

p – 0.8 p = 8.4.

0.2p = 8.4.

p = 8.4: 0.2 = 84: 2 = 42 (cm).

Method II.

The first side is 0.35 of the perimeter, which means it is 35% of the perimeter.

The two sides are 35% + 45% = 80% of the perimeter.

This means the third party is 100% – 80% = 20% of the perimeter.

We make the proportion:

20% = 8.4 cm,

100% = x cm (we take the entire perimeter as 100%).

x = 8.4 * 100: 20 = 840: 20 = 42 (cm).

Answer: The perimeter of the triangle is 42 cm.



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