Shortcut Trick
In similar triangles, the ratio of their areas is equal to the square of the ratio of their corresponding sides.
Given BD || AE, ΔBDC is similar to ΔAEC (ΔBDC ~ ΔAEC).
Ratio of sides BD : AE = 3 : 8.
⇒ Ratio of Area(ΔBDC) : Area(ΔAEC) = (3)2 : (8)2 = 9 : 64.
∴ The correct answer is 9 : 64.
Alternate Method
Given:
In ΔACE, BD || AE and AE/BD = 8/3.
Formula Used:
If two triangles are similar, the ratio of their areas is the square of the ratio of their corresponding sides.
Calculations:
In ΔBDC and ΔAEC:
⇒ ∠C = ∠C (Common angle)
⇒ ∠CBD = ∠CAE (Corresponding angles as BD || AE)
⇒ ∠CDB = ∠CEA (Corresponding angles as BD || AE)
⇒ ∴ ΔBDC ~ ΔAEC (By AAA similarity criterion)
⇒ Area(ΔBDC) / Area(ΔAEC) = (BD / AE)2
⇒ Given AE/BD = 8/3 → BD/AE = 3/8
⇒ Area(ΔBDC) / Area(ΔAEC) = (3 / 8)2
⇒ Area(ΔBDC) / Area(ΔAEC) = 9 / 64
∴ The correct answer is 9 : 64.
Additional Information
Similar Triangles Properties
If two triangles are similar, the ratio of their altitudes, medians, and perimeters is equal to the ratio of their corresponding sides.
Thales Theorem (BPT)
A line drawn parallel to one side of a triangle divides the other two sides in the same ratio (CB/BA = CD/DE).
Area Ratio Rule
For any two similar figures, the ratio of their areas is always the square of the ratio of any linear dimension (side, radius, etc.).