tolong dibantu jwb plus caranya please ...

AB = √7²-2²
AB = √49 - 4
AB = √45
AB = √9 × 5
AB = 3√5 cm

Luas Bidang OABC
= 2 x  L∆OAB
= 2 x (1/2 x a x t)
= 2 x (1/2 x 2 x 3√5)
= 2 x (3√5)
= 6√5 cm² (C)

Semoga Membantu!!!

OB = 7 cm
OA = OC = 2 cm
BC = AB = √(OB² - OA²)
= √(7²-2²)
= √(49-4)
= √45 = 3√5 cm

Luas OABC
= luas OAB + luas OBC
= (½×OA×AB) + (½×OC×BC)
= (½×2×3√5) + (½×2×3√5)
= 3√5 + 3√5
= 6√5 cm²