Recent content by Velcroe

Thanks so much for your help. That makes a lot of sense.

Sorry let me fix it. Prove a(b-c)=ab-ac let x=b-c existence of subtraction (axiom) x+c=b (part of the subtraction axiom) a[(x+c)-c] substitution which is never spelled out but used repeatedly in books proofs so I assume its allowed a[x+(c-c)] associative property axiom a[x+0] existence of...

I am currently working my way though Calculus by Tom Apostol. One of the really early proofs ask the reader to prove: a(b-c)=ab-ac. Here is what I did, I let x=b-c which by the definition of subtraction equals x+c=b. Substituting that value into the right hand side I got...

Actually my mistake in quoting the question. It actually states"... may be drawn the the three vertices of any triangle". Sorry about that don't know how I mistyped that. Fixed my original question.

That makes sense, so the answer to Gelfand question quoted above would just be 5. Seems like the question is too easy which is why I asked my question in the first place. Well thank you for your response.

I am reading Gelfand's Trigonometry. In one of the questions he asks: "We know from geometry that a circle may be drawn through the three vertices of any triangle. Find the radius of such a circle if the sides of the triangle are 6,8, and 10." My first question is, I know that if the diameter...