SOLUTION: The sum of angles of a triangle is 180degree and Exterior angle of a triangle is equal to sum of interior opposite angle.

Question 642235: The sum of angles of a triangle is 180degree and Exterior angle of a triangle is equal to sum of interior opposite angle.
Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!
I guess, you need a proof.

1. angle ACE ie exterior angle of triangle ABC.....| given
2. mA+mB+mACB=180..............................................|the sum theorem
3. m ACE +m ACB=180........................................|def. of linear pair
4. mA+mB+mACB=m ACE +mACB........................|transitive property
5. mA +mB=m ACE.........................................|subtraction property

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