Question: 14. Given a circle of radius = 7 cm, find the length of a 90° arc. Round to 2 d.p.
1. **State the problem:** We need to find the length of an arc of a circle with radius $7$ cm and central angle $90^\circ$.
2. **Formula for arc length:** The length $L$ of an arc with radius $r$ and central angle $\theta$ (in degrees) is given by:
$$L = 2 \pi r \times \frac{\theta}{360}$$
3. **Substitute the values:** Here, $r = 7$ cm and $\theta = 90^\circ$. Using $\pi = 3.14$ as instructed:
$$L = 2 \times 3.14 \times 7 \times \frac{90}{360}$$
4. **Simplify the fraction:**
$$\frac{90}{360} = \frac{1}{4}$$
5. **Calculate the arc length:**
$$L = 2 \times 3.14 \times 7 \times \frac{1}{4}$$
6. **Multiply step-by-step:**
$$2 \times 3.14 = 6.28$$
$$6.28 \times 7 = 43.96$$
$$43.96 \times \frac{1}{4} = \cancel{43.96} \times \frac{1}{\cancel{4}} = 10.99$$
7. **Final answer:** The length of the $90^\circ$ arc is $10.99$ cm (rounded to 2 decimal places).