I WILL AWARD BRAINLIEST Given: AC = AB, CD = DE

m∠ABC = 70°, m∠ ECB = 35°

Prove: DE ║BC

m∠ACB = m∠, By reason ( Base angles theorem, Exterior Angle theorem, Supplementary angles, Vertical Angles theorem ) - choose one

a) By Base angle theorem

b)DE||BC since and they are alternate interior angles

Step-by-step explanation:

Given: AC = AB, CD = DE

∠ABC = 70°, m∠ ECB = 35°

Refer the attached figure

AB = AC

So, By Base angle theorem : if the sides of a triangle are congruent then the angles opposite these sides are congruent.

So,

So,      ----1

CD = DE

So, by Base theorem

Let  be x

So,

Using 1

70 = x+35

35=x

Now

So, DE||BC since and they are alternate interior angles

answer: i'm great at algebra

~coco

step-by-step explanation: