Which cannot be used in a proof?
a. theorems
b. postulates
c. properties
d. undefined terms

D.Undefined Terms

Step-by-step explanation:

The reason in a mathematical proof can be a given information, vocabulary definitions, properties, postulates or previously proved theorems.

But the undefined terms are the terms which used in geometry to define other terms.

Therefore , the undefined terms cannot be used in a mathematical proof .

Hence , D is the correct option.

answer: the answer is one of

step-by-step explanation:   we are given to write a proper fraction where the whole is divided into an even number of equal parts less than ten, and an odd number of those parts exist.

an even number less than 10 may be one of 2, 4, 6 or 8. so, the whole may be one of these four evens.

now, an odd number of these parts must exist, so the numerator must be an odd number, one of 1, 3, 5 or 7. it cannot be 9 because then the fraction will become improper.

thus, our fraction may be one of the following

abde or 1,2,4, 5 is the answer

step-by-step explanation: