What is the area of the quadrilateral bounded by y=5y=5; x=1x=1; y=1y=1; and y=-2x+9y=−2x+9?

1 Answer
Alan P.
Dec 29, 2017

88 square units

Explanation:

Note that y=-2x+9y=−2x+9 can be written as x=(9-y)/2x=9−y2
making it easier to evaluate the intersection coordinates for
y=-2x+9y=−2x+9 and y=5y=5
color(white)(y=-2x+9)y=−2x+9 and y=1y=1
enter image source here

From the above diagram it is clear that the area is

color(white)("XXX")color(blue)4 xx (color(blue)1 + color(blue)3)/2XXX4×1+32

color(white)("XXX")=8XXX=8

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