AlgebraHardArea of a triangle formed by three lines
Algebra practice question
In the xy-plane, the lines y = 2x, y = −2x, and y = 8 form a triangle. What is the area of the triangle?
Answer: 32
y = 8 meets y = 2x at (4, 8) and y = −2x at (−4, 8); the other two lines meet at the origin. Base 8 (from −4 to 4) and height 8: area = (1/2)(8)(8) = 32.
Common wrong answers
- If you answered 8
- 8 is the height alone.
- If you answered 16
- 16 uses a base of 4.
- If you answered 64
- 64 forgets the 1/2.
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