jika sudut AOB 90° dan jari lingkaran 10cm luas tembereng AB diarsir adalah....

Luas juring AOB = (90°/360°) x π r²
                           = (90°/360°) x 3,14 x 10²
                           = 78,5 cm²
Luas segitiga = 1/2 alas x tinggi
                      = 1/2 x 10 x 10
                      = 50 cm²
Luas tembereng = Luas juring - Luas segitiga
                           = 78,5 - 50
                           = 28,5 cm²