The expanded angle was divided into two angles in a ratio of 1: 4 to find the degree measure of the obtuse angle.

Let’s calculate how many parts the expanded angle was divided into:

1 + 4 = 5 parts – the unfolded corner was divided into this number of parts.

The corner is considered obtuse, in which there are more parts.

Let’s calculate how many parts make up an obtuse angle from both angles:

4: 5 = 4/5 pieces – makes an obtuse angle from these two corners.

The unfolded angle is 180 °.

Let’s find what the obtuse angle is equal to, making the proportion:

180 ° – 1,

J – 4/5.

J = 180 * 4/5: 1;

J = 144: 1;

J = 144 ° – makes an obtuse angle.

Answer: The degree measure of an obtuse angle is 144 °.