kasih tau dong jawaban nomor 12dan3

1. Ini tentang segiempat tali busur ya(sudut2 yg berhadapan berjumlah 180°)
2x +3x =180°
5x =180°
x=180°/5
x =36°

y +110°=180°
y=180°-110°
y=70°
a. x=36° dan y=70°
b. 3x - 4y+5x =8x - 4y = 8.36° - 4.70°
= 288°-280°
=8°

[tex]2. \: l \: juring = \frac{p \: busur}{k \: lingkaran} \times l \: lingkaran \\ = \frac{22cm}{2 \times \frac{22}{7} \times 21cm} \times \frac{22}{7} \times (21cm {)}^{2} \\ = 11 \times 21 {cm}^{2} \\ = 231 {cm}^{2} [/tex]
3. L diarsir = L. Juring - L. L segitiga
=90/360 x 3,14 x(20cm)^2 - 1/2x 20cm x20cm
=314cm^2 - 200cm^2
=114cm^2