ACT Math 4.2 Plane Geometry
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ACT Math: Plane Geometry Drill 4, Problem 2. If x, y, and z are all integer values, which of the following cannot be the ratio of x:y:z?
|ACT Math||Plane Geometry|
|ACT Mathematics||Plane Geometry|
|Foreign Language||Arabic Subtitled|
|Plane Geometry||Properties of plane figures|
|Product Type||ACT Math|
aren't fractions or decimals. We also know that
the sum of a triangle's angles always equal 180 degrees. So... since the ratios of the
angles are always relative to 180 degrees, we have to look for the ratio that can't
allow the angles to be integers. In English, that basically means that, since
we're dividing up 180 degrees into little parts...
...180 has to be divisible by the total number
of parts in the ratio. The question is asking for the ratio that
can't be possible, so we have to look for the one that isn't divisible by 180. Let's
try: A: 1 + 2 + 3 = 6 and 180 / 6 = 30
B: 1 + 2 + 2 = 5, 180 / 5 = 36 C: 1 + 1 + 2 = 4, 180 / 4 = 45
D: 1 + 2 + 4 = 7, 180 / 7 = 25.715 E: 1 + 2 + 6 = 9, 180 / 9 = 20
Our answer is D because it doesn't produce an integer value, which means that each part
is not an integer, which ultimately means that the angles can't be integers either.