Question

state and prove Thalis theorem?​

Answer 1

Step-by-step explanation:

In geometry, Thales's theorem states that if A, B, and C are distinct points on a circle where the line AC is a diameter, then the angle ∠ABC is a right angle.

Answer 2

ANSWER

Statement: If a line is drawn parallel to one side of a triangle, to interest the other two sides at indistinct points, the other two sides are divided in the same ratio.

Given: - In △ABC,DE∥BC

To prove:- AD/DB = AE/EC

Construction:- BE and CD are joined. EF⊥AB and DN⊥AL

are drawn.

Proof:-

ar(△ADE) = 1/2×AD×EF

=1/2×AE×DN

ar(△BDE) = 1/2×BD×EF

ar(△CDE) = 1/2×EC×DN

ar(△ADE)/ar(△BDE) = 1/2×AD×EF/1/2×BD×EF ........(1)

ar(△ADE)/ar(△CDE) = 1/2×AE×DN/1/2×EC×DN ........(2)

But, ar(△BDE) = ar(△CDE) ..............(3)

as they are on the same base DE and DE∥BC

from (1), (2) and (3) we get AD/DB = AE/EC

Step-by-step explanation:

Hope it helps