1)
Geoff’s Parallelogram
Area = 144cm2
Height = 10cm
Base = ?
Height X Base = Area
Area ÷ Height = Base
144 ÷ 10 = 14.4
Base = 14.4cm
Lynn’s Triangle
Area = 144cm2
Base = 12cm
Height = ?
Height X Base ÷ 2 = Area
144 ÷ 12 X 2 = 12 X 2 = 24
Height = 24 cm
Brian’s parallelogram
Height = 20cm
Base = 15cm
Area = ?
Height X Base = Area
20 X 15 = 300
Area = 300cm2
Brian’s triangle
Height = 20cm
Base = half of parallelogram’s base = 7.5
Area = ?
Height X Base ÷ 2 = Area
20 X 7.5 ÷ 2 = 150 ÷ 2 = 75
Area = 75
Area not covered by triangle = 300cm2 – 75cm2 = 225cm2
225cm2 of the parallelogram is not covered by the triangle.
2)
On any triangle (except for the isosceles triangle because there are two equal sides,) the base line is the longest line (but because the isosceles triangle has 2 equal sides, the base line is the line not equal to the other sides). The height line is 90 degrees from the base line and is usually inside the shape but you don’t see the actual line, unless it is a right angle triangle. The 90 degree angle is important because The height just can’t be any random line on the triangle that’s facing up or the second longest. It has to be 90 degrees from the base line because the height line is facing the top and bottom. The base is the bottom.
Excellent Justin - really well explained! Great process, good detail, nice use of formulas to help solve the process.
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Mr.B