Q. To verify that the interior angle of a triangle is equal to the sum of the two interior opposite angles.

 Hi!

Here is the answer to your query.

 

In ΔABC

∠A + ∠B + ∠C = 180°       [Angle sum property ]      .....(1)

Also

∠C + ∠BCD = 180°             [Linear Pair ]       ....... (2)

 

Equating (1) and (2)

∠C + ∠BCD = ∠A + ∠B + ∠C

∠BCD = ∠A + ∠B

 

Hence, exterior angle of a triangle is equal to sum of two interior opposite angles.

 

Cheers!

  • 1
What are you looking for?