# Change of Subject in Mathematics

**Change of Subject in Mathematics **

- To make ‘r’ the subject of the formula in v = πr², you divide both sides by π and then take the square root of both sides. So, r = √(v/π).
- To make ‘b’ the subject of the formula in A = 1/2bh, you multiply both sides by 2 and then divide both sides by ‘h’. So, b = 2A/h.
- To make ‘x’ the subject of the formula in x² = a, you take the square root of both sides. So, x = √a.
- For compass bearings: a. Point SE turning 25 degrees clockwise means it’s facing 25° clockwise from the south direction. So, the angle is 25°. In three-figure bearing, it’s S25°E. b. Point S turning 48 degrees clockwise means it’s facing 48° clockwise from the south direction. So, the angle is 48°. In three-figure bearing, it’s S48°E. 🧭

Evaluation questions:

- To make ‘r’ the subject of the formula in v = πr², we __________ both sides by π and then take the square root of both sides. a) multiply b) divide c) subtract d) add
- To make ‘b’ the subject of the formula in A = 1/2bh, we __________ both sides by 2 and then divide both sides by ‘h’. a) add b) subtract c) multiply d) divide
- To make ‘x’ the subject of the formula in x² = a, we __________ both sides by taking the square root. a) multiply b) divide c) add d) subtract
- Point SE turning 25 degrees clockwise indicates an angle of __________. a) 25° b) 35° c) 45° d) 55°
- Point S turning 48 degrees clockwise indicates an angle of __________. a) 18° b) 28° c) 38° d) 48°
- To make ‘v’ the subject of the formula in v = πr², we __________ both sides by π. a) add b) subtract c) multiply d) divide
- To make ‘b’ the subject of the formula in A = 1/2bh, we __________ both sides by ‘h’. a) multiply b) divide c) add d) subtract
- To make ‘x’ the subject of the formula in x² = a, we __________ both sides by taking the square root. a) multiply b) divide c) add d) subtract
- In compass bearings, S25°E means __________ degrees clockwise from the south direction. a) 25 b) 50 c) 75 d) 100
- In compass bearings, S48°E means __________ degrees clockwise from the south direction. a) 48 b) 96 c) 144 d) 192
- To make ‘r’ the subject of the formula in v = πr², we __________ both sides by π. a) add b) subtract c) multiply d) divide
- To make ‘b’ the subject of the formula in A = 1/2bh, we __________ both sides by ‘h’. a) multiply b) divide c) add d) subtract
- To make ‘x’ the subject of the formula in x² = a, we __________ both sides by taking the square root. a) multiply b) divide c) add d) subtract
- In compass bearings, S25°E means __________ degrees clockwise from the south direction. a) 25 b) 50 c) 75 d) 100
- In compass bearings, S48°E means __________ degrees clockwise from the south direction. a) 48 b) 96 c) 144 d) 192

**Class Activity Discussion **

- How do I make ‘r’ the subject of the formula in v = πr²?
**Answer:**You divide both sides by π and then take the square root of both sides.

- How do I make ‘b’ the subject of the formula in A = 1/2bh?
**Answer:**You multiply both sides by 2 and then divide both sides by ‘h’.

- How do I make ‘x’ the subject of the formula x² = a?
**Answer:**You take the square root of both sides.

- What does S25°E mean in compass bearings?
**Answer:**It means turning 25 degrees clockwise from the south direction.

- What does S48°E indicate in compass bearings?
**Answer:**It indicates turning 48 degrees clockwise from the south direction.

- How do I isolate ‘v’ in the formula v = πr²?
**Answer:**You divide both sides by π.

- How do I find ‘b’ in the formula A = 1/2bh?
**Answer:**You multiply both sides by 2 and then divide by ‘h’.

- How do I solve for ‘x’ in x² = a?
**Answer:**You take the square root of both sides.

- What’s the angle when Point SE turns 25 degrees?
**Answer:**The angle is 25 degrees clockwise.

- What’s the angle when Point S turns 48 degrees?
**Answer:**The angle is 48 degrees clockwise.

- How do I rearrange the formula v = πr² to solve for ‘r’?
**Answer:**Divide both sides by π and then take the square root.

- How do I rearrange the formula A = 1/2bh to find ‘b’?
**Answer:**Multiply both sides by 2 and then divide by ‘h’.

- How do I find ‘x’ in the equation x² = a?
**Answer:**Take the square root of both sides.

- What’s the direction when the compass bearing is S25°E?
**Answer:**The direction is 25 degrees clockwise from south.

- What’s the direction indicated by S48°E in compass bearings?
**Answer:**It indicates a direction 48 degrees clockwise from south.