jika panjang OA=2 cm dan panjang OB= 7cm mak Luas bidang OABC adalah?

AB⁲ = OB⁲ - OA⁲.
AB = √OB⁲ - OA⁲.
AB = √7⁲ - 2⁲.
AB = √49 - 4.
AB = √45.
AB = √9 × 5.
AB = 3√5cm.

L. ∆OAB
= 1/2 × a × t.
= 1/2 × 2 × 3√5.
= 1/2 × 6√5.
= 3√5cm⁲.

L. OABC
= 2 × ∆OAB.
= 2 × 3√5
= 6√5cm⁲.

Jawaban : C.