So their areas are equal.
So the area of △AOB is equal to the area of △COD.
So the area of delta delta △AOB is 6.
Because the OB of △COD and △COB is equal to the height of OD side.
So their area ratio is equal to the bottom ratio.
So the ratio of OD and OB is 6: 12 = 1: 2.
Because OB of △AOD and △AOB is equal to the height of OD side.
So their area ratio is equal to the bottom ratio.
Therefore, the ratio of △AOD to △AOB is equal to the ratio of OD to OB = 1: 2.
So the area of △AOD is equal to half the area of △AOB = 3.
So the areas of the other two triangles are 3 and 6 respectively.
Junior high school knowledge answer:
Because s △ OCD: s △ OCB = OD: OB
So OD/OB = 6/ 12 = 1/2.
Because AD//BC
So △AOD∽△COB
So s △ AOD: △ COB = (OD/OB) 2 = 1/4.
So s △ AOD: 12 = 1/4.
So s △ aod = 3.
Because s △ AOB: △ Cob = OA/OC = OD/OB.
So s △ AOB: 12 = 1/2.
So s △ AOB = 6
So the areas of the other two triangles are 3 and 6 respectively.
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