Question 452082: The sum of the measures of three of the interior angles of a pentagon is 280. The measure of the fourth angle is three times the measure of the fifth. Find the measure of the fourth angle?
Answer by pedjajov(51)   (Show Source):
You can put this solution on YOUR website! The sum of the angles in pentagon is 540.
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So if fourth angle is x and fifth is y we have
280+x+y=540
x=3y -> y=x/3
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Substitute y into first equation
280+x+x/3=540, multiply by 3
840+3x+x=1620, subtract 840 from both sides, combine x
4x=780, divide by 4 both sides
x=195, this is measure of the fourth angle
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check:
280+195+195/3 = 540, ok
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