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25 votes
Triangles

Calculate the perimeter of ABC​

Triangles Calculate the perimeter of ABC​-example-1
User Anuresh Verma
by
3.1k points

1 Answer

22 votes
22 votes

Answer:

40 units.

Explanation:

Consider ∆ADC

Perimeter = 26cm (Given)

★ Perimeter of a triangle is the sum of its three sides.

=> AD + DC + AC = 26

Now, from the figure we can see that side AD = DC

Hence we can also write

=> AD + AD + AC = 26

=> 2AD + AC = 26

=> AC = 26 - 2AD ——— ‘1’

Consider ∆ ABC,

Let us consider it's perimeter to be ‘x’.

=> AB + AC + BC = x

Here also we can make out from the figure that side AB = BC

=> AB + AB + AC = x

=> 2AB + AC = x

From ‘1’ substituting AC value, we get

=> 2AB + ( 26 - 2AD ) = x

=> 2AB - 2AD + 26 = x

=> 2( AB - AD ) + 26 = x

=> 2 (7) + 26 = x ( Given )

Therefore perimeter of the ∆ABC (x) = 40

User Caleb Seadon
by
2.9k points
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