Multiple Geometry Algebra
1. **Solve inequality:** $3 + x > 5$
Subtract 3 from both sides:
$$x > 5 - 3$$
$$x > 2$$
So, $x$ must be greater than 2.
2. **Circle problem (diameter 28 cm):**
Diameter $d = 28$ cm, radius $r = \frac{28}{2} = 14$ cm.
(i) Circumference $C = 2 \pi r = 2 \times 3.14 \times 14 = 87.92$ cm (approx).
Given is 176 cm, which is incorrect. Response: "x".
(ii) Area $A = \pi r^2 = 3.14 \times 14^2 = 3.14 \times 196 = 615.44$ cm$^2$ (approx).
Given is 616 cm$^2$, which is approximately correct. Response: "✓".
3. **Angle equality problem:**
Given $\widehat{APC} = \widehat{BPD}$, show $\widehat{APB} = \widehat{CPD}$.
Since $\widehat{APC} = \widehat{BPD}$ and points are arranged appropriately, this forms vertical or alternate angles implying $\widehat{APB} = \widehat{CPD}$ by the properties of intersecting lines.
4. **Triangle ABC with PQ parallel to BC through A:**
Since $PQ \parallel BC$, corresponding angles are equal.
Thus, $\widehat{BAC} = \widehat{PAQ}$.
Using the triangle and parallel line properties, angle $\widehat{BAC}$ is equal to the alternate interior angle formed by PQ and BC.
5. **Bearing calculations:**
(i) Bearing of B from A is the clockwise angle from north at A towards B.
(ii) Bearing of A from B is the clockwise angle from north at B towards A.
Exact bearing values depend on diagram specifics not given numerically, so general explanation provided.
6. **Refrigerator pricing:**
Selling price (SP) = 72,810; Discount = 10%
(i) Marked price (MP) is such that SP = MP - 10% of MP = 0.9 MP.
So, $0.9 \times MP = 72,810$; hence,
$$MP = \frac{72,810}{0.9} = 81,000$$
(ii) Discount = MP - SP = 81,000 - 72,810 = 8,190
7. **Mean and range of numbers:**
Numbers: 17, 15, 18, $x$, 13; Mean = 16
(i) Sum of numbers = $5 \times 16 = 80$
Sum is $17 + 15 + 18 + x + 13 = 63 + x$
Set equal:
$$63 + x = 80$$
$$x = 17$$
(ii) Range = Max - Min
With $x=17$, numbers are 13, 15, 17, 17, 18
Max = 18, Min = 13
Range = $18 - 13 = 5$
Final answers summarized:
- Inequality: $x > 2$
- Circle responses: (i) "x", (ii) "✓"
- Angle proof: $\widehat{APB} = \widehat{CPD}$
- Angle $\widehat{BAC}$ equals alternate interior angle with PQ parallel to BC.
- Bearings explained qualitatively.
- Marked price = 81,000; Discount = 8,190
- Missing number $x=17$; Range = 5