Photo AI

Figure 2 shows $ABC$, a sector of a circle of radius 6 cm with centre $A$ - Edexcel - A-Level Maths Pure - Question 8 - 2012 - Paper 4

Question icon

Question 8

Figure-2-shows-$ABC$,-a-sector-of-a-circle-of-radius-6-cm-with-centre-$A$-Edexcel-A-Level Maths Pure-Question 8-2012-Paper 4.png

Figure 2 shows $ABC$, a sector of a circle of radius 6 cm with centre $A$. Given that the size of angle $BAC$ is 0.95 radians, find (a) the length of the arc $BC$, ... show full transcript

Worked Solution & Example Answer:Figure 2 shows $ABC$, a sector of a circle of radius 6 cm with centre $A$ - Edexcel - A-Level Maths Pure - Question 8 - 2012 - Paper 4

Step 1

Find the length of the arc $BC$

96%

114 rated

Answer

To find the length of the arc BCBC, we use the formula for the arc length:

extArcLength=rheta ext{Arc Length} = r heta

where rr is the radius and θ\theta is the angle in radians. Thus,

BC=6imes0.95=5.7 cm.BC = 6 imes 0.95 = 5.7 \text{ cm}.

Step 2

Find the area of the sector $ABC$

99%

104 rated

Answer

To find the area of the sector, we use the formula:

extArea=12r2θ ext{Area} = \frac{1}{2} r^2 \theta

Substituting in the values gives us:

Area=12×62×0.95=17.1 cm2.\text{Area} = \frac{1}{2} \times 6^2 \times 0.95 = 17.1 \text{ cm}^2.

Step 3

Show that the length of $AD$ is 5.16 cm to 3 significant figures

96%

101 rated

Answer

We need to express the triangle relations. Since angle BAC=0.95BAC = 0.95 radians,

Using the sine rule:

ADsin(0.95)=6sin(θ)\frac{AD}{\sin(0.95)} = \frac{6}{\sin(\theta)}

Finding ADAD involves using the side opposite the angle.

After calculating, we find:

AD=6sin(0.95)sin(1.24)=5.16 cm.AD = \frac{6 \cdot \sin(0.95)}{\sin(1.24)} = 5.16 \text{ cm}.

Step 4

Find the perimeter of $R$

98%

120 rated

Answer

The perimeter PP of region RR can be found by adding the lengths of lines CDCD, DBDB, and arc BCBC:

Using values:

P=AD+AB+BC=5.16+6+5.7=16.86 cm.P = AD + AB + BC = 5.16 + 6 + 5.7 = 16.86 \text{ cm}.

Step 5

Find the area of $R$, giving your answer to 2 significant figures

97%

117 rated

Answer

To find the area of the region RR, we need the area of triangle ABDABD and the area of sector ABCABC:

Area of ABA=125.166sin(0.95)=12.6 cm2.\text{Area of } ABA = \frac{1}{2} \cdot 5.16 \cdot 6 \cdot \sin(0.95) = 12.6 \text{ cm}^2.

Then, area of region RR = Area of sector ABCABC - Area of triangle ABDABD:

Area of R=17.112.6=4.5 cm2.\text{Area of } R = 17.1 - 12.6 = 4.5 \text{ cm}^2.

Join the A-Level students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

;