Question

Which biconditional is not a good definition?

Two angles are supplementary if and only if the sum of their angles measures 180.
Two angles are vertical angles only if they are not adjacent to each other and are formed by two intersecting lines.
Two angles form a linear pair if and only if the angles are adjacent.
The sum of two angles is 90 if and only if those two angles are complementary.

Answer 1

You need to read each statement and see if the converse is also true.
If the converse is also true, then the biconditional is a good definition.

Answer 2

Let's use the first one as an example.
Statement: Two angles are supplementary if the sum of their measures is 180 degrees.
Converse: If the sum of the measures of two angles is 180, then the angles are supplementary.
Both the statement and the converse are true, so the first biconditional is a good definition.

Answer 3

Now do the same to each of the the other 3 statements, and find the one whose converse is not true.

Answer 4

D?

Answer 5

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