Question

A carpenter's square is placed over a board as shown in the figure to the right. If 1 measures 77° what is the size of 2?

Answer 1

To solve this question we will use the following diagram as reference:

Notice that angles 1 and 2 are consecutive exterior angles, therefore they must add up to 180 degrees, meaning:

`\measuredangle1+\measuredangle2=180^(\circ).`

We know that ∠1 measures 77°, therefore:

`77^(\circ)+\measuredangle2=180^(\circ)\text{.}`

Subtracting 77° from the above equation we get: