# Special Triangles - Need to know?

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Hey,

Do I need to know these rules for special triangles?

90-45-45

Sides Ratio

Isosceles: x : x : x

90-60-30

Sides Ratio

x : x : 2 x

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Yes, absolutely!  You also need to know the 3,4,5 right triangle and the 5, 12, 13 right triangle.

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I'll also add that the formula for the area of an equilateral triangle sometimes comes in handy.

If the length of each side is L, then the area is:

sqrt3(L^2)/4

Cheers,

Brent

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Yes. Learn them up to the point that they are basically automatic to you.

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I think these triangles, plus the basic probability (combinations and permutations), will get you through at least half the problems and almost all of the difficult ones.

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I think these triangles, plus the basic probability (combinations and permutations), will get you through at least half the problems and almost all of the difficult ones.

I think "half" might be a bit of a stretch

The test-makers are more interested in evaluating one's competency regarding real-life topics such as statistics, percent, and number sense.

Cheers,

Brent

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I think "half" might be a bit of a stretch

The test-makers are more interested in evaluating one's competency regarding real-life topics such as statistics, percent, and number sense.

Cheers,

Brent

I was lucky - I'd enrolled in Stats 2.1x on edx to upgrade my statistics literacy before doing research this summer. I took the GRE today without much preparation, and the 3 lectures (the online course just started) helped me tremendously with means, medians, etc.!

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Yes, there are one or two questions on triangles on most exams it would seem.

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