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August 22, 2014

August 22, 2014

Posted by **Tsunayoshi** on Monday, June 9, 2014 at 8:27am.

And can you please tell me how to prove it in drawing....

- Algebra -
**Reiny**, Monday, June 9, 2014 at 9:10amYour diagram should show that you have a right angle at B , but let's prove it anyway.

slope AB = (2-1)/(5-1) = 1/4

slope of BC = (6-2)/(4-5) = -4

YES, AB is perpendicular to BC, thus AC is a hypotenuse

midpoint of AC = M( (1+4)/2 , (1+6)/2) = M(5/2 , 7/2)

= M(2.5 , 3/5)

AM = √(1.5^2 + 2.5^2 = √8.5

CM = √(1.5^2 + 2.5^2) = √8.5 , clearly has to be, since we found the midpoint

BM = √((5 - 2.5)^2 + (2-3.5)^2 ) = √8.5

YUP, all is good

If you make a good sketch, you should be able to show it by counting the displacements along the grid pattern

- Algebra -
**tsunayoshi**, Monday, June 9, 2014 at 9:31amWhat is the solution when the formula used is distance between points??

- Algebra -
**Reiny**, Monday, June 9, 2014 at 10:04amI don't understand your question.

I DID use the distance between two points formula, I just did not show the subtraction since that is easily done in your head.

here is one of them with all steps :

AM = √( 2.5 - 1)^2 + (3.5-1)^2 )

= √( 1.5^2 + 2.5^2)

= √2.25 + 6.25)

= √8.5 ---- see above

= appr 2.9155

- Algebra -
**Tsunayoshi**, Monday, June 9, 2014 at 10:25amI mean is to get the distance of A B C you used distance formula not slope...

- Algebra -
**Reiny**, Monday, June 9, 2014 at 11:06amI think the main purpose of the question, even though they did not say that, was to show that the midpoint of the hypotenuse is equidistant from the 3 vertices.

All I did with the slope calculation was to show that the triangle is indeed right-angled.

Other than that, finding the slope had nothing to do with the calculations of the distances.

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