Question

Why can two acute angles be supplementary?

Answer 1

They cannot.
Their sum must be `180^o` to be supplementary, but it will be less than `180^o` because each acute angle is less than `90^o`.

Explanation:

Angles `/_A` and `/_B` are supplementary if their sum measures `180^o`.

Acute angle are those measured less than `90^o`.

If `/_A<90^o` and `/_B<90^o` then
`/_A+/_B < 180^o`

Therefore, two acute angle cannot be supplementary to each other.