All rhombuses have 2 pairs of parallel sides.
Answer:
A. T > 2.539
Step-by-step explanation:
We have a hypothesis test of the mean, with unknown population standard deviation.
The hypothesis are:

From the hypothesis we can see that the test is right-tailed, so the critical value of t should be a positive value.
The degrees of freedom can be calculated as:

The significance level is 0.01, so the critical value tc should be the one that satisfies:

Looking up in a t-table, for 19 degrees of freedom, this critical value is tc=2.539.
Answer:
8 cm and 9 cm
Step-by-step explanation:
The other two sides added together have to equal a larger number than 13, since 13 is the largest side.
5 + 8 = 13
6 + 7 = 13
7 + 2 = 9
8 + 9 = 17