Two or more angles are called *complementary* angles when together they add up to 90°

In the example above ∠ADB and ∠BDC are complementary since together they add up to 90°.

Of course ∠ADC = 90°

Two or more angles are called *supplementary* when they add up to 180°

In the example above ∠x and ∠y are supplementary since together they add up to 180°

## soooooooo

How do we know how to add up an angle

## maria valenzuela

the way my old teacher showed me was u have the degrees of the angle, so u just subtract a number from that and add an number to it and if it adds up right, now not all the time will it work but for the most it help me.

## CatreshaP.

Can you send me an example on how to plug in the angles? Thanks