4. determine whether the statement is true or false. prove the statement directly from the definition if it is true, and give a counterexample if it is false. the average of two odd integers is odd.

The statement is false.

Step-by-step explanation:

Let a and b represent two odd integers.

The average (A) is defined by:

A=

In order to prove the statement, you have to show that it's true for all odd integers. But, to disprove it, you just have to find a counterexample where the statement is false.

Notice that it is easier to try to find a counterexample.

For example, a=3 and b=5

A=

The result of the average is even, therefore the statement is false.

The previous calculation is a counterexample.

  21.3

step-by-step explanation:

multiplying the given equation by c/sin(25°), we get

  c = 9/sin(25°) ≈ 21.2958 ≈ 21.3

we assume "c" is the length of ab, the side opposite angle c in triangle abc.