How to check the angle sum property of triangle.
TRIANGLES Solutions for Class 9th Maths.
9th Maths EXERCISE 7.2,Page No:124, Questions No:5.
Class 9th ,NCERT Books for Session 2023-2024, based on CBSE Board.
ABC and DBC are two isosceles triangles on the same base BC (see Figure). Show that ∠ ABD = ∠ ACD.
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In ΔABC,
AB = AC [∵ Given]
∠ABC = ∠ACB …(1) [∵ Angles opposite to equal sides are equal]
In ΔDBC,
DB = DC [∵ Given]
∠DBC = ∠DCB …(2) [∵ Angles opposite to equal sides are equal]
Adding equation (1) and (2), we get
∠ABC + ∠DBC = ∠ACB + ∠DCB
⇒ ∠ABD = ∠ACD.