JIka sudut pusat lingkaran 90° dan jari-jarinya 7cm Tentukan A.Luas juring AOB B.Luas Tembereng AB

a.Ljuring
[tex] = \frac{ \alpha }{360} \times \pi {r}^{2} \\ = \frac{90}{360} \times \frac{22}{7} \times {7}^{2} \\ = 38.5 \: cm {}^{2} [/tex]
b.L tembereng
[tex] =Ljur-Lsgitiga \\= 38.5 - \frac{1}{2} \times {r}^{2} \times sin \alpha \\ = 38.5 - \frac{1}{2} \times {7}^{2} \times sin90 \\ = 38.5 - 24.5 \\ = 14 cm {}^{2} [/tex]

(A)
L.AOB = (α/360)πr²
L.AOB = (90/360)22/7.7²
L.AOB = 90/360 . 154
L.AOB = 38,5 cm²

(B)
L = (α/360)πr² – ½ r² sin α
L = (90/360)(22/7)7² – ½ .7² sin 90°
L = 38,5 – 24,5
L = 14 cm²