Know Your Keywords — Math, Advanced
Point 11 — Perpendicular drawn inside a right triangle
What do we see?
A right-angled triangle with a perpendicular drawn inside it.
What do we understand?
Label the angles as θ, 90 − θ, and 90, then use trigonometric ratios — or the similar-triangle relations BD2 = AD · DC and AB2 = AD · AC.
Tips & traps
Stub errors here come from taking incorrect ratios — label every angle before writing one.
Question 1 of 3
In the figure shown above, AD = and AB = . What is the length of DC?