Question

Use the diagram, which is not drawn to scale, to decide which proportions are true.

Triangles A D B and C D B share side D B.
I. StartFraction D B Over D C EndFraction = StartFraction D A Over D B EndFraction
II. StartFraction B A Over C B EndFraction = StartFraction C B Over B D EndFraction
III. StartFraction C A Over B A EndFraction = StartFraction B A Over C A EndFraction
IV. StartFraction D B Over B C EndFraction = StartFraction D A Over B A EndFraction

a.
I and IV only
c.
I and II only
b.
II only

Answer 1

I and IV only.

Explanation:

There are 3 similar triangles in the diagram, so corresponding sides are in the same ratio. You can identify corresponding sides by checking that the angles opposite them are congruent.