Question

Angle CBD has a measure of 140 degrees. What is the measure of angle ABD?

Answer 1

Recall that the sum of angles on a straight line is 180 degrees.

Therefore, for the line AC, it can be deduced that:

`m\angle ABD+m\angle CBD=180\degree`

The question provides the following angle measure:

`m\angle CBD=140\degree`

Substituting the angle measure into the formula, the unknown angle can be solved as follows:

`\begin{gathered} m\angle ABD+140\degree=180\degree \\ m\angle ABD=180\degree-140\degree \\ m\angle ABD=40\degree \end{gathered}`

ANSWER

`\begin{equation*} m\angle ABD=40\degree \end{equation*}`