Geometry homework - accuracy check

[Jessica]

Help me with these or check them. I may add more for you.


1. The perimeter and the ratio of the length to the width of a rectangle are given. Find the length and width of the rectangle.

P = 132 cm
l : w = 7 : 4

work/answer-

2(7x) + 2(4x) = 132
14x + 8x = 132
x=6

the length = 32
width = 24

2. The measures of the angles of a triangle are in the extended ratio given. Find the measures of the angles of the triangle.

3 : 4 : 10

work/answer-

20x = 180
x=9

measures: 27, 63, 90


Check these answers for now. I will/may have more later. :wicked: :lol:

[Fazor]

Probably too late to help; but the answer to #2 is not in the correct ratio. Though, with the ratio you listed (3:4:10) the angles don't end up as whole numbers. I suspect the ratio is suppose to say 3:7:10, in which case your answer is right, or at least looks right to me.

[Zwarte Piet]

I don't think you're doing these right. For the first one, if the length and width are in a 7:4 ratio, then it can't be 32:24. That would be a 4:3 ratio.

[Fazor]

I don't think you're doing these right. For the first one, if the length and width are in a 7:4 ratio, then it can't be 32:24. That would be a 4:3 ratio.
Good catch; but she did it correctly, there's just an error in multiplication.


If x = 6, then 7x = 42, not 32.

[Zwarte Piet]

Another good catch^

Fazor is right about number 2. A 3:4:10 ratio cannot be correct because it would not be a triangle. One of the triangle rules is that the sum of any two sides must be greater than the third side. A 3:4:10 ratio would not pass this rule.

[Jessica]

my homework is not due until Monday. It's a packet.

[Fazor]

No me gustaba (?) tarea que era debida (?) en los lunes.

[Rusty]

No me gustaba (?) tarea que era debida (?) en los lunes.No me gustaba la tarea que tenía que entregar los lunes.
No me gustaba la tarea que debe entregarse los lunes.

[Jessica]

huh? what does that mean?

I am aware of my mistakes. and yes, the ratio is supposed to be 3 : 7 : 10. I made a mistake while typing this :P same with the multiplication.

[Jessica]

No me gustaba (?) tarea que era debida (?) en los lunes.

Does that mean you don't like the homework to be due on Monday? Why not? It's pretty long.

[Fazor]

I *didnt* like it, no. It's been a while since I've had homework. :) I just hated having homework over the weekend.

[Jessica]

oh. well we got it on Tuesday last week, so yeah. I just finished it today. it was hard, but I finished it. most of them require pictures, though, so I won't be able to let you check them.

Here's another one:

The scale of a map and the distance between two points on the map is given. Find the actual distance between the locations represented by the points.

Scale: 4 in. : 1 mi.
Map distance: 10.5 inches

Is this right, what I did?

4 in/1 mi = 10.5 in/x mi

4x = 10.5
x = 2.625 mi

[Zwarte Piet]

Yes sir, that is correct!

[Fazor]

Actually, it's not.

X is the scalar (or whatever it's called).
You know that 4 inches is a (1) mile, so that's the fact you want to work with first.

It's 4X = 1, or x = .5 (miles).
Then it's a simple matter of multiplying the distance between two points (10.5) by X.

So, you approached the problem correctly, but you used the wrong number to find X.

[sosia]

I'm not a mathematician, but I don't see why is not OK what jchen did.
It's a "regla del tres"

[Fazor]

You're right. Her way works too. My mistake.
I would have done 4x = 1, therefore x = .25.
10.5 * .25 = 2.625.

So the answer is the same, just the method is diferent.

[Jessica]

I crossed multiplied then solved for x. That's what I did. :)

[Zwarte Piet]

Ya, that's probably the simpler method.