Gruber's Math Workbook Help

matt110029 · 11-14-2012, 07:34 PM

Does anyone have Gruber's Math Workbook that can help me understand the problem on page 268.

((1/2)(AB)h)/((1/2)(AB)h)=1/3

Why is the second AB not AD since its the base of the whole triangle? And where did the 1/3 come from?

matt110029 · 11-14-2012, 07:36 PM

By the way, I understand why it's 1/3 because the lines trisect the whole triangle in three equal parts which mean the area of one part is a third of the whole, but I want to understand it the way they did it in case I encounter more complex problems.

Reckie · 11-14-2012, 08:06 PM

The second.. what?

matt110029 · 11-14-2012, 08:13 PM

I mean't the bottom of the fraction.

Reckie · 11-14-2012, 08:21 PM

Oh no you're right; it should be AD.

Otherwise the answer would be 1. Which would be wrong.
x/x=1

Grubers has tons of mistakes.

matt110029 · 11-14-2012, 08:25 PM

Thanks! I thought I was missing something, but apparently not. This would've saved me much more time if I knew that earlier.

matt110029 · 11-15-2012, 04:04 PM

Wait, I don't think it was a mistake because he talks about how the AB cancels out. But, I just don't understand where the equation came from. Anyone else have Gruber's Math Workbook that can help?