Question

Question #9c6b3

Answer 1

Read below.

Explanation:

Let's draw this case. I made one in Paint.

Let's draw a line parallel to line AC. We now have:

Using our rules on angles formed by parallel lines and by their transcendental line, we can label the following:

We could name the anlge BAC as `x` and Angle BCA as `180-90-x` or `90-x`

Let's consider triangle DBC. We know that the sum of the interior angles of a triangle is 180 degrees or `pi` radians. We do not know the measure of the angle DBC(we name it `y`), so let's write an equation.
`y=180-90-(90-x)` we simplify this to get:
`y=x`
Since we know that `x` is equal to the angle BAC, we now know that angle DBC is congruent to angle BAC.