Triangle Area Ratio: Finding the Proportion when AD is a Median

To solve this problem, we'll focus on the role of the median $AD$.

• Since $AD$ is a median, it divides side $BC$ into two equal parts, meaning $D$ is the midpoint.
• The property of a median in a triangle is that it divides the triangle into two smaller triangles of equal area.
• Thus, $\triangle ABD$ and $\triangle ADC$ will have the same area.

Therefore, the ratio of the area of $\triangle ABD$ to the area of $\triangle ADC$ is $1:1$.