Answer:
The correct matrices are:
Matrix:
7 1 5
1 5 7
5 7 1
all diagonal elements of A^2 are: 7^2 + 1^2 + 5^2
Matrix:
9 18 27
27 -9 18
18 27 9
all diagonal elements of A^2 are: 9^2 + 27*18 + 18*27 or (-9)^2
Matrix:
8 1 6
6 8 1
1 6 8
all diagonal elements of A^2 are: 8^2 + 6*1 + 1*6
Given:
In a right angle triangle ABC,
, and 
To find:
The value of AC.
Solution:
In a right angle triangle,




On cross multiplication, we get



Therefore, the measure of AC is 12.304 m.
For question 4, 
Question 5. Option a and question 6. Option j
Step-by-step explanation:
Step 1:
The three basic formula needed to solve these questions are:

Step 2:
Using the above formula, we solve the following values









Step 3:
For question 5, The triangle's angle = 23°, opposite side = BC inches and hypotenuse = 4 inches.

SO BC is 1.5628 inches, rounding this off to the nearest tenth, we get BC = 1.6 inches which is option a.
Step 4:
For question 6, The triangle's angle = 50°, opposite side = QR m the adjacent side = 8.1 m.

SO QR is 9.65277 meters, rounding this off to the nearest tenth, we get QR = 9.7 inches which is option j.
The 2nd one. The one that says CD=DA, DA=ZX, AC=YZ