Are you referring to the area of oblique and right triangles?
On oblique triangles,
you just need to find the BASE, and the HEIGHT.
If it was given, then it's really easy to solve the equation.
The formula is:
A = (H x B) / 2
Example:
Height = 2
Base = 4
A = (2 * 4) / 2
A = 8 / 2
A = 4
On right triangles,
you just have to know the value of A, OR HEIGHT, and B, or base.
The formula is:
A = AB / 2
Example:
A/HEIGHT = 2
B/BASE = 4
A = 2 * 4 / 2
A = 8 / 2
A = 4