What is the area of a triangle contained by the points A (0, 0), B (7, 0), and C (0, 4)?
Hint
This is a very right triangle.
Answer
14 units2
Example 2
A right triangle has an area of 60 units2. If the vertex of its right angle is at the origin and it has another vertex at (12, 0), where can its final vertex be plotted?
Hint
The distance from the origin to (12, 0) is 12 units long.
Answer
(0, 10) or (0, -10)
Example 3
A circle has a center at (4, -3) and a point P (0, 0). What is the area of the circle?
Hint
The distance formula is your best friend here.
Answer
25π ≈ 78.5 units2
Example 4
A trapezoid has vertices (corners) at the points A (0, 0), B (0, 10), C (12, 4), and another point D. If the area of the trapezoid is 48 units2 and AB is one of the bases, what are the coordinates of D?
Hint
Since we've got a trapezoid, we know DC needs to be parallel to AB.
Answer
D (-2, 4)
Example 5
The diameter of a circle reaches from (-1, 9) to (3, 3). What is the area of the circle?