Hitunglah luas PQR jika diketahui: 1. p 12cm, q 9cm, r 15cm.. 2. p 14cm, q 14cm, r 14cm.. 3. p 10cm, q 7cm, r 13cm??

1) s. miring = 15 cm, karena sisi yg paling panjang
sisi siku" = 12 cm dan 9 cm
[tex] \frac{siku \: 1\times siku2}{2} = \frac{12 \times 9}{2} = 54 \: cm {}^{2} [/tex]
2) L. segitiga sm sisi
[tex] \frac{1}{4 }s {}^{2} \sqrt{3} = \frac{1}{4} \times 14 {}^{2} \sqrt{3} = \frac{1}{4} \times 196 \sqrt{3} \\ = 49 \sqrt{3} \: {cm}^{2} [/tex]
3) sisi miring = 13 cm
alas = 10 cm
tinggi = 7 cm
[tex] \frac{a \times t}{2} = \frac{10 \times 7}{2} = 35 \: cm {}^{2} [/tex]

DIK
.L=a×t/2
1) =12cm×9cm/2
=54 cm2
2)14cm×7cm/2
=49 cm2
3)10cm×7cm/2
=35cm2