View Full Version : Triangle Help

osbornes

09-18-2005, 12:30 PM

In triangle ABC, find the measure of <C if:

m<C=3m<A=3m<B

I put

x+3x+3x=180degrees

9x=180degrees

m<a-20degrees, m<b=20degrees

answer

180-40=140 degrees thus m<c=140degrees

Is this correct?

'Fraid not. Droping the m< (which seems unnecessary to me. C is the number of degrees in angle C) you have

C=3A=3B so

A=C/3

B=C/3

C=3C/3

A+B+C=180 giving

(C+C+3C)/3 = 180

BTW. DO NOT mix c and C in the same problem. c and C are two different variables.

Denis

09-18-2005, 02:31 PM

x+3x+3x=180degrees

9x=180degrees

be CAREFUL; that should be 7x, not 9x !

tkhunny

09-19-2005, 09:21 AM

In triangle ABC, find the measure of <C if:

m<C=3m<A=3m<BIt appears that this could be:

C=3A and A = 3B

A+B+C = 180º

A+B+3A = 180º

3B+B+3(3B) = 180º

3B+B+9B = 180º

13B = 180º

I'm willing to be wrong.

?????????????

To me it says 3A=3B. Can't read it any other way :evil:

------------------

Gene

tkhunny

09-19-2005, 12:48 PM

It could be just me. My primary programming language (interpreted) parses from right to left. If I made assignments like this:

c <= 3*a <= 3*b

It would be as I have stated it, first making the assignment a = 3*b, then the assignment c = 3*a

Multiple equals always are dangerous. There isn't a precedence level for equals -- EPEMDAS? PEMDASE? :)

I can't point to a website but forever I have interpreted

a=b=c as

a=b and

b=c and

a=c

Under any reading I don't see how you can drop the 3 from the b in

3b=3c to get b=3c

which your method would seem to require. Is that reverse Polish?

BTW: I have learned from other posts that

m>B means

"the measure of angle B"

not "m is greater than B"

As I said, it has always seemed extranious to me.

-------------------

Gene

stapel

09-19-2005, 02:48 PM

I have to agree with Gene.

Eliz.

Denis

09-19-2005, 05:25 PM

m<C=3m<A=3m<B

Now, the teacher that gives this to a student should be shot at sunrise!

I can defend this analysis of the mess:

measure of angle C = 3 times measure of angle A;

then 3 times measure of angle A = 3 times measure of angle B,

so angle A = angle B;

so we have 3x + x + x = 180; 5x = 180; x = 36; A=108, B=36, C=36

So yours truly maintains that that stupid expression means:

in triangle ABC, angle A is 3 times angle B, and angle B = angle C

tkhunny

09-19-2005, 05:41 PM

Is that reverse Polish?No, it's just very strict right-to-left interpretation, under the assumption that variable names cannot begin with a numeric character. Once it hits the "3" and realizes that is the end of an expression, it has no choice but to assign "a" without yet recognizing the "3".

I'll be the first to admit that it takes a little getting used to.

I think Dennis hit the nail on the head with this one. That whole expression, as originally reported, is just a mess. If it was from the student, just trying really hard to get everything in, that is fine. The student can learn. If it was from the teacher, well, perhaps a bit of peer review would have helped.

Ya got me. I would have bet a quarter that I had at least a nodding acquaintance with any programming language discussed. Fortran, Cobol, 5 Basic dialects, RPG, PLO, APL, Lisp, Assembler... At one time or another I've at least dabbled in them. But yours stops me cold.

-------------------

Gene

tkhunny

09-19-2005, 06:54 PM

Ummm...You had better read up on APL a little more. I wasn't going to tell.

stapel

09-19-2005, 06:57 PM

Meanwhile, is the original poster ever going to reply with clarification?

Eliz.

tkhunny

09-19-2005, 10:29 PM

Just for the HiJack conversation, I also remember Cornell's Compiler for PL/1 (Vintage 1975?). If you typed anything illegal, it would try to guess what you meant. Sometimes it was an adventure.

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