The measure of two complementary angles adds up to 90°. Therefore, the measure of the complementary angle of an 87° angle can be found by subtracting 87° from 90°:

$90^\circ - 87^\circ = 3^\circ$

So, the measure of the complementary angle is 3°.

Would you like more details or have any questions?

Here are 5 related questions for further practice:

1. What is the complementary angle of a 35° angle?
2. If two angles are complementary and one measures 45°, what is the measure of the other?
3. Can two obtuse angles be complementary? Why or why not?
4. What is the complementary angle of a 60° angle?
5. If an angle measures 25°, what is the sum of its complementary and supplementary angles?

Tip: Always remember that complementary angles add up to 90°, while supplementary angles add up to 180°.