Solve the Proportion: Finding the Missing Term in AD/_ = AE/AC

Question

BC is parallel to DE.

Fill in the gap:

$\frac{AD}{}=\frac{AE}{AC}$

00:07 Let's fill in what's missing.

00:10 Notice, the lines are parallel, just as given.

00:15 For parallel lines, matching, or corresponding angles, are equal. We call this angle A.

00:23 And here, another corresponding angle is equal. Let's call this angle A2.

00:29 So, the triangles are similar because of Angle-Angle, or AA.

00:35 Now, corresponding sides face these equal angles. This helps us understand their relationship.

00:55 And that's how we solve this question!

00:59 Now, let's move on to the next chapter.

Since we are given that line BC is parallel to DE

Angle E equals angle C and angle D equals angle B - corresponding angles between parallel lines are equal.

Now let's observe that angle D is opposite to side AE and angle B is opposite to side AC, meaning:

$\frac{AE}{AC}$

Now let's observe that angle E is opposite to side AD and angle C is opposite to side AB, meaning:

$\frac{AD}{AB}$