What is the area of a triangle with vertices (1,1), (3,1), and (5,7)?

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6

×
7

×
9

×
10

×
12
What is the area of a triangle with vertices (1,1), (3,1), and (5,7)?
6
7
9
10
12
Plot the triangle as description. It turns out the triangle is an obtuse triangle.
Make the perpendicular line from the vertex (5,7) to the base.
The area of the triangle is,
A = \dfrac{1}{2}bh= \dfrac{1}{2}\times2\times 6=6