Soalan 1:
Hitung lilitan bulatan yang mempunyai
(a) jejari 7 cm.
(b) jejari 56 cm.
(c) diameter 9.2 cm.
(d) diameter 98 mm.
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
$$ \begin{aligned} & \text { Lilitan }=\pi \times \text { diameter } \\ & =\pi d \end{aligned} \begin{aligned} \text { Atau, Lilitan } & =\pi \times 2 \times \text { jejari } \\ & =2 \pi j \end{aligned} $$
(a)
$$ \begin{aligned} & \text { Jejari } 7 \mathrm{~cm} \\ & \begin{aligned} \text { Lilitan } & =2 \pi j \\ & =2 \times \frac{22}{7} \times 7 \\ & =44.00 \mathrm{~cm} \end{aligned} \end{aligned} $$
(b)
$$ \begin{aligned} &\text { Jejari } 56 \mathrm{~cm}\\ &\begin{aligned} \text { Lilitan } & =2 \times \frac{22}{7} \times 56 \\ & =352.00 \mathrm{~cm} \end{aligned} \end{aligned} $$
(c)
$$ \begin{aligned} &\text { Diameter } 9.2 \mathrm{~cm}\\ &\begin{aligned} \text { Lilitan } & =\pi d \\ & =\frac{22}{7} \times 9.2 \\ & =28.91 \mathrm{~cm} \end{aligned} \end{aligned} $$
(d)
$$ \begin{aligned} &\text { Diameter } 98 \text { mm }\\ &\begin{aligned} \text { Lilitan } & =\pi d \\ & =\frac{22}{7} \times 98 \\ & =308.00 \mathrm{~mm} \end{aligned} \end{aligned} $$
Hitung lilitan bulatan yang mempunyai
(a) jejari 7 cm.
(b) jejari 56 cm.
(c) diameter 9.2 cm.
(d) diameter 98 mm.
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
$$ \begin{aligned} & \text { Lilitan }=\pi \times \text { diameter } \\ & =\pi d \end{aligned} \begin{aligned} \text { Atau, Lilitan } & =\pi \times 2 \times \text { jejari } \\ & =2 \pi j \end{aligned} $$
(a)
$$ \begin{aligned} & \text { Jejari } 7 \mathrm{~cm} \\ & \begin{aligned} \text { Lilitan } & =2 \pi j \\ & =2 \times \frac{22}{7} \times 7 \\ & =44.00 \mathrm{~cm} \end{aligned} \end{aligned} $$
(b)
$$ \begin{aligned} &\text { Jejari } 56 \mathrm{~cm}\\ &\begin{aligned} \text { Lilitan } & =2 \times \frac{22}{7} \times 56 \\ & =352.00 \mathrm{~cm} \end{aligned} \end{aligned} $$
(c)
$$ \begin{aligned} &\text { Diameter } 9.2 \mathrm{~cm}\\ &\begin{aligned} \text { Lilitan } & =\pi d \\ & =\frac{22}{7} \times 9.2 \\ & =28.91 \mathrm{~cm} \end{aligned} \end{aligned} $$
(d)
$$ \begin{aligned} &\text { Diameter } 98 \text { mm }\\ &\begin{aligned} \text { Lilitan } & =\pi d \\ & =\frac{22}{7} \times 98 \\ & =308.00 \mathrm{~mm} \end{aligned} \end{aligned} $$
Soalan 2:
Diberi lilitan bulatan 24.5 cm. Hitung
(a) diameter
(b) jejari
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 3.142)
Penyelesaian:
(a)
$$ \begin{aligned} & \text { Lilitan }=\pi d \\ & 3.142 \times d=24.5 \\ & \qquad \begin{aligned} d & =\frac{24.5}{3.142} \\ & =7.80 \mathrm{~cm}(2 . \mathrm{t} . \mathrm{p}) \end{aligned} \end{aligned} $$
(b)
$$ \begin{aligned} & \text { Lilitan }=2 \pi j \\ & \begin{aligned} 2 \times 3.142 \times j & =24.5 \\ j & =\frac{24.5}{6.284} \\ & =3.90 \mathrm{~cm} \quad(2 . \mathrm{t} . \mathrm{p}) \end{aligned} \end{aligned} $$
Diberi lilitan bulatan 24.5 cm. Hitung
(a) diameter
(b) jejari
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 3.142)
Penyelesaian:
(a)
$$ \begin{aligned} & \text { Lilitan }=\pi d \\ & 3.142 \times d=24.5 \\ & \qquad \begin{aligned} d & =\frac{24.5}{3.142} \\ & =7.80 \mathrm{~cm}(2 . \mathrm{t} . \mathrm{p}) \end{aligned} \end{aligned} $$
(b)
$$ \begin{aligned} & \text { Lilitan }=2 \pi j \\ & \begin{aligned} 2 \times 3.142 \times j & =24.5 \\ j & =\frac{24.5}{6.284} \\ & =3.90 \mathrm{~cm} \quad(2 . \mathrm{t} . \mathrm{p}) \end{aligned} \end{aligned} $$
Soalan 3:
Hitung luas bulatan yang mempunyai jejari berikut.
(a) 21 m
(b) 56 mm
(c) 7 cm
(d) 1 2/5 cm
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
(a)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times 21^2 \\ & =1386.00 \mathrm{~m}^2 \end{aligned} $$
(b)
$$ \begin{aligned} \text { Luas } & =\pi r j^2 \\ & =\frac{22}{7} \times 56^2 \\ & =9856.00 \mathrm{~mm}^2 \end{aligned} $$
(c)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times 7^2 \\ & =154.00 \mathrm{~cm}^2 \end{aligned} $$
(d)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times\left(1 \frac{2}{5}\right)^2 \\ & =\frac{22}{7} \times\left(\frac{7}{5}\right)^2 \\ & =6.16 \mathrm{~cm}^2 \end{aligned} $$
Hitung luas bulatan yang mempunyai jejari berikut.
(a) 21 m
(b) 56 mm
(c) 7 cm
(d) 1 2/5 cm
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
(a)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times 21^2 \\ & =1386.00 \mathrm{~m}^2 \end{aligned} $$
(b)
$$ \begin{aligned} \text { Luas } & =\pi r j^2 \\ & =\frac{22}{7} \times 56^2 \\ & =9856.00 \mathrm{~mm}^2 \end{aligned} $$
(c)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times 7^2 \\ & =154.00 \mathrm{~cm}^2 \end{aligned} $$
(d)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ & =\frac{22}{7} \times\left(1 \frac{2}{5}\right)^2 \\ & =\frac{22}{7} \times\left(\frac{7}{5}\right)^2 \\ & =6.16 \mathrm{~cm}^2 \end{aligned} $$
Soalan 4:
Luas bagi sebuah bulatan ialah 38.5 cm2. Hitung
(a) jejari
(b) lilitan bagi bulatan
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
(a)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ \pi j^2 & =38.5 \\ \frac{22}{7} \times j^2 & =38.5 \\ j^2 & =38.5 \times \frac{7}{22} \\ j^2 & =12.25 \\ j & =\sqrt{12.25} \\ j & =3.50 \mathrm{~cm} \end{aligned} $$
(b)
$$ \begin{aligned} \text { Lilitan } & =2 \pi j \\ & =2 \times \frac{22}{7} \times 3.50 \\ & =22.00 \mathrm{~cm} \end{aligned} $$
Luas bagi sebuah bulatan ialah 38.5 cm2. Hitung
(a) jejari
(b) lilitan bagi bulatan
Berikan jawapan dalam dua tempat perpuluhan. (Guna π = 22/7 )
Penyelesaian:
(a)
$$ \begin{aligned} \text { Luas } & =\pi j^2 \\ \pi j^2 & =38.5 \\ \frac{22}{7} \times j^2 & =38.5 \\ j^2 & =38.5 \times \frac{7}{22} \\ j^2 & =12.25 \\ j & =\sqrt{12.25} \\ j & =3.50 \mathrm{~cm} \end{aligned} $$
(b)
$$ \begin{aligned} \text { Lilitan } & =2 \pi j \\ & =2 \times \frac{22}{7} \times 3.50 \\ & =22.00 \mathrm{~cm} \end{aligned} $$