Figure 2 shows a flag XYWZ - Edexcel - A-Level Maths Pure - Question 6 - 2018 - Paper 4
Question 6
Figure 2 shows a flag XYWZ.
The flag consists of a triangle XYZ joined to a sector ZYW of a circle with radius 5 cm and centre Y.
The angle of the sector, angle ZY... show full transcript
Worked Solution & Example Answer:Figure 2 shows a flag XYWZ - Edexcel - A-Level Maths Pure - Question 6 - 2018 - Paper 4
Step 1
a) the area of the sector ZYW in cm²
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Answer
To find the area of the sector ZYW, we can use the formula:
A=21r2θ
where:
r = 5 cm (radius)
( \theta = 0.7 ) radians.
Substituting the values into the formula:
A=21×52×0.7=21×25×0.7=8.75 cm2
Step 2
b) the area of the flag, in cm², to 2 decimal places
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Answer
The area of the flag consists of the area of the sector ZYW and the area of triangle XYZ.
Area of Triangle XYZ:
Using the formula for the area of a triangle:
A=21×base×height
Here, we can consider XY as the base (7 cm) and use the height as the radius of the sector (5 cm):
AXYZ=21×7×5=17.5 cm2
Total Area of the Flag:
Now, combining both areas:
Total Area=Asector+Atriangle=8.75+17.5=26.25 cm2
So, rounding to 2 decimal places, the area of the flag is 26.25 cm².
Step 3
c) the length of the perimeter, XYWZ, of the flag, in cm to 2 decimal places
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Answer
To find the perimeter of the flag XYWZ, we need to sum the lengths of all sides:
From the point Y to X: 7 cm (given).
From Y to W: 5 cm (given).
Length ZW can be found using Pythagoras’ Theorem. Since ZY is the opposite side of angle ZYW:
Using the sine function:
\approx 3.22 \text{ cm} $$
Length XZ can be calculated using the cosine function:
\approx 7 \times 0.764
\approx 5.35 \text{ cm} $$
Now, adding these lengths together:
= 7 + 5 + 3.22 + 5.35 \
= 20.57 \text{ cm} $$
So, rounding to 2 decimal places, the length of the perimeter is **20.57 cm**.