The sides of this triangle are 7 cm, 5 cm and 4 cm. Find the sides of a similar triangle if its small side is 1.5 cm.

| November 29, 2020 | education

We know that similar triangles are triangles with two angles that are equal (1 sign of similarity) and their sides of one triangle are proportional to the corresponding sides of the second triangle.
We are given: Side 1 = 7 cm, side 2 = 5 cm, side 3 = 4 cm, and all this is the first triangle. We also know that the smallest side of such a triangle = 1.5 cm.
So let’s compare the sides of the first triangle: 7 is more than 5 and more than 4, 5 is more than 4 – hence 4 is the smallest side of the first triangle.
Let x be the longest side of the second triangle, y the middle side of the second triangle. Let’s compose the proportion (/ – division or dash):
7 / x = 5 / y = 4 / 1.5
Knowing how the proportions are solved, we can find first y and then x.
(The proportion is solved crosswise):
4y = 7.5
y = 1.875 cm
We also find x:
5x = 1.875 * 7
5x = 13.125
x = 2.625 cm
Answer: 1.875 cm, 2.625 cm



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