Buku Teks Matematik Tingkatan 2 (KSSM) – Jom Cuba 7.1 (Soalan 4 – 6)


Soalan 4:
Diberi jarak mengufuk 4 unit dan jarak mencancang 3 unit bagi dua titik A dan B, hitung nilai a dan b.


Penyelesaian:

\(\begin{aligned} a-(-1) & =4 \\ a+1 & =4 \\ a & =4-1 \\ a & =3 \\ b-0 & =3 \\ b & =3\end{aligned}\)


\(\begin{aligned} 5-a & =4 \\ -a & =4-5 \\ -a & =-1 \\ a & =1 \\ b-1 & =3 \\ b & =3+1 \\ b & =4\end{aligned}\)



\(\begin{aligned} 2-a & =4 \\ -a & =4-2 \\ -a & =2 \\ a & =-2 \\ b-(-1) & =3 \\ b+1 & =3 \\ b & =3-1 \\ b & =2\end{aligned}\)


\(\begin{aligned} 0-a & =4 \\ -a & =4 \\ a & =-4 \\ 4-b & =3 \\ -b & =3-4 \\ -b & =-1 \\ b & =1\end{aligned}\)


Soalan 5:

Rajah menunjukkan titik K, L, M, N, P dan Q pada satah Cartes.
Hitung jarak di antara titik yang berikut.
(a) KM
(b) ML
(c) PN
(d) KQ


Penyelesaian:

Jarak \(=\sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2}\)

(a)
\(\begin{aligned} \text { Jarak } K M & =\sqrt{(1-(-3))^2+(4-8)^2} \\ & =\sqrt{(1+3)^2+(-4)^2} \\ & =\sqrt{4^2+(-4)^2} \\ & =\sqrt{16+16} \\ & =\sqrt{32} \\ & =5.66 \text { unit }\end{aligned}\)

(b)
\(\begin{aligned} \text { Jarak ML } & =\sqrt{(6-1)^2+(7-4)^2} \\ & =\sqrt{5^2+3^2} \\ & =\sqrt{25+9} \\ & =\sqrt{34} \\ & =5.83 \text { unit }\end{aligned}\)

(c)
\(\begin{aligned} \text { Jarak } P N & =\sqrt{(2-(-3))^2+(1-(-4))^2} \\ & =\sqrt{(2+3)^2+(1+4)^2} \\ & =\sqrt{5^2+5^2} \\ & =\sqrt{25+25} \\ & =\sqrt{50} \\ & =7.07 \text { unit }\end{aligned}\)

(d)
\(\begin{aligned} \text { Jarak } K Q & =\sqrt{(3-(-3))^2+(-3-8)^2} \\ & =\sqrt{(3+3)^2+(-11)^2} \\ & =\sqrt{6^2+(-11)^2} \\ & =\sqrt{36+121} \\ & =\sqrt{157} \\ & =12.53 \text { unit }\end{aligned}\)



Soalan 6:
Tentukan jarak KL jika K (2, 2) dan L berada pada paksi-x dengan jarak 7 unit ke kanan dari paksi-y.

Penyelesaian:
Diberi L berada pada paksi-x, maka koordinat y bagi titik L = 0.
Diberi juga jarak titik L adalah 7 unit ke kanan dari paksi-y (x positif), maka koordinat bagi titik L = (7, 0).

\(\begin{aligned} & \text { Jarak } K L \\ & =\sqrt{(7-2)^2+(0-2)^2} \\ & =\sqrt{5^2+(-2)^2} \\ & =\sqrt{25+4} \\ & =\sqrt{29} \\ & =5.39 \text { unit }\end{aligned}\)


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