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If ABC~DEF and the perimeter of ABC is 4 times greater than the

perimeter of DEF, what is the relationship between the areas of the
triangles?

1 Answer

3 votes

Answer:

The area of triangle ABC is 16 times larger than the area of triangle DEF

Explanation:

Step 1: Re-state the input

Given two triangles ABC and DEF are similar with ratio k.

Step 2: Derive the information

Suppose that the triangle ABC is k times larger than triangle DEF.

=> It means that all sides and heights of triangle ABC are k times larger than corresponding sides and heights of triangle DEF.

For example:

AB = k x DE

AC = k x DF

BC = k x EF

=> AB + AC + BC = k x (DE + DF + EF)

=> Perimeter of triangle ABC is k times larger than perimeter of triangle DEF

Step 3: Solve the problem step-by-step

Suppose that AH is the height from vertex A to base BC of triangle ABC and DH' is the height from the vertex D to base EF of triangle DEF.

As the above assumption states:

AH = k x DH'

BC = k x EF

Multiply both sides of the two above equations:

=> AH x BC = DH x EF x k x k

Simplify k components:

=> AH x BC = DH x EF x k^2

Multiply (1/2) to both sides:

=> (1/2) x AH x BC = (1/2) x DH x EF x k^2

Apply the formula to calculate the area of a triangle:

=> Area of triangle ABC = Area of triangle DEF x k^2

In other words:

The area of triangle ABC is (k^2) times larger than area of triangle DEK.

Here, the perimeter of triangle ABC is 4 times larger than the perimeter of triangle DEF => k = 4

Step 4: Make the conclusion

=>The area of triangle ABC is (4^2 = 16) times larger than area of triangle DEK.

Hope this helps!

:)

User Vladimir Stazhilov
by
3.5k points