Answer:
7a) QS = 16 units
7b) 96 square units
8) 30 units
Explanation:
Question 7a
The sides lengths of a rhombus are equal.
Therefore, if the rhombus has a perimeter of 40, each side length is 10, since 40 ÷ 4 = 10.
PQ = QR = RS = SP = 10
The diagonals of a rhombus are perpendicular bisectors of each other.
Therefore, if PR is 12, then PM = 6.
Also, if QM + MS = QS, and QM = MS, then QS = 2·QM.
As the diagonals bisect each other at right angles, triangle PMQ is a right triangle, where:
Using Pythagoras Theorem to find the length of QM:





As QS = 2·QM, then:



Question 7b
The formula for the area of a rhombus is half the product of its diagonals.

Therefore, given the diagonals of the rhombus are PR = 12 and QS = 16, the area of the rhombus is:


Question 8
The formula for the perimeter of a rhombus given its diagonals is:

If the diagonals are 9 and 12, the perimeter is:

Therefore, the perimeter of the rhombus is 30 units.