MEDAL AND FAN

1. The slope of line m is -1/12 . The slope of a line perpendicular to line m is __________

2. Find the measure of AB.

Question

MEDAL AND FAN



1. The slope of line m is -1/12 . The slope of a line perpendicular to line m is __________

2. Find the measure of  AB.

natalie1234 · Answer

attachment

natalie1234 · Answer

thats for number 2

mathmate · Answer

hint:
If two lines are perpendicular, the product of the two slopes equals -1.
For example, 
L1: y = 2x +3
L2: y = -(1/2)x -2
Then L1 is perpendicular to L2 because the product of slopes 2 and -(1/2) 
= (2)*(-1/2) = -1

natalie1234 · Answer

my choices are 
      Option A: –12
       Option B: -1/12
       Option C: 1/12
       Option D: 12

mathmate · Answer

Hints for question 2, 
triangles XMN and XAB are similar, and the ratio of similitude is 2, i.e. all dimensions of XAB are twice the corresponding dimensions of XMN.
Similarly, triangle XMN and XZY are similar, with ratio of similitude equal to 3.

natalie1234 · Answer

so is it a?

dtan5457 · Answer

It's not a because you forgot to switch the sign.

natalie1234 · Answer

so its d then?

dtan5457 · Answer

Yes

natalie1234 · Answer

thank you! and for number 2? I still need help with that one

natalie1234 · Answer

is it 30?

dtan5457 · Answer

Do you have a given theorem or formula? I don't remember it.

natalie1234 · Answer

umm idk let me ask @mathmate

dtan5457 · Answer

Because they look like trapezoids. $$\frac{ 5x+45 }{ 2 }=8x+8$$

dtan5457 · Answer

Solve for x, can you do it? Once you get x, you can get the lengths of MN and AB.

mathmate · Answer

Yes, use @dtan5457's equation, or
since by similar triangles, AB=2*MN, so
2(5x)=8x+8
the value of x comes to the same thing.
For your information, your suggested answer for AB is correct.