Triangles Ratio
1. The problem states that the two shapes have equal areas. We are asked to find the ratio $k : m$.
2. The left shape is a right-angled triangle with base $k$ cm and height 12 cm. Its area is
$$\text{Area}_{\text{triangle}} = \frac{1}{2} \times k \times 12 = 6k.$$
3. The right shape is an L-shape composed of two rectangles stacked vertically. The width of both rectangles is $m$. The heights are 2 cm and 3 cm respectively. Hence, the total height is $2 + 3 = 5$ cm. One side length is labeled $k$, which matches the width of the taller part.
4. The total area of the L-shape is the sum of the areas of the two rectangles:
$$\text{Area}_{\text{L-shape}} = m \times 2 + m \times 3 = 5m.$$
5. Since the areas are equal:
$$6k = 5m.$$
6. To find the ratio $k : m$, isolate $k/m$:
$$\frac{k}{m} = \frac{5}{6}.$$
7. Therefore,
$$k : m = 5 : 6.$$
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8. Next, for question 9, the graph of the quadratic function is given:
$$y = 0.5x^2 - 6x + 12.$$
9. The problem involves analyzing this parabola. To understand its key features:
10. Find the vertex using the formula:
$$x = -\frac{b}{2a} = -\frac{-6}{2 \times 0.5} = \frac{6}{1} = 6.$$
11. Calculate $y$-value at $x=6$:
$$y = 0.5(6)^2 - 6(6) + 12 = 0.5 \times 36 - 36 + 12 = 18 - 36 + 12 = -6.$$
12. The vertex is at $(6, -6)$. Since $a=0.5 > 0$, the parabola opens upwards.
13. Find the $y$-intercept by evaluating $y$ at $x=0$:
$$y = 0.5 \times 0 - 6 \times 0 + 12 = 12.$$ So the $y$-intercept is $(0,12)$.
14. Find the $x$-intercepts by solving $0 = 0.5x^2 - 6x + 12$:
Multiply all terms by 2:
$$0 = x^2 - 12x + 24.$$
15. Use the quadratic formula:
$$x = \frac{12 \pm \sqrt{(-12)^2 - 4 \times 1 \times 24}}{2} = \frac{12 \pm \sqrt{144 - 96}}{2} = \frac{12 \pm \sqrt{48}}{2} = \frac{12 \pm 4\sqrt{3}}{2} = 6 \pm 2\sqrt{3}.$$
These are the two $x$-intercepts.
16. Summary:
- Vertex: $(6, -6)$ (minimum point)
- $y$-intercept: $(0, 12)$
- $x$-intercepts: $(6 - 2\sqrt{3}, 0)$ and $(6 + 2\sqrt{3}, 0)$
This information matches the graph described.