For a right triangle, the sum of the squares of two shorter side should be equal to the square of the third side. The calculations for each choices are shown below.
a. (5 mm)² + (12 mm)² = 169 mm² ; (13 mm)² = 169 mm² ; EQUAL
b. (20 mm)² + (48 mm)² = 2704 mm² ; (52 mm)² = 2704 mm² ; EQUAL
c. (6 mm)² + (8 mm)² = 100 mm² ; (10 mm)² = 100 mm² ; EQUAL
d. (11 mm)² + (24 mm)² = 697 mm² ; (26 mm)² = 676 mm² ; NOT EQUAL
Therefore, the answer is letter D.
Answer: 
<u>Step-by-step explanation:</u>

Answer:
84 different lineups are possible
Step-by-step explanation:
The order in which the songs are chosen is not important. So we use the combinations formula to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

In this question:
6 musics from a set of 9. So

84 different lineups are possible