Question

If AC = 36 and BC = 18, find AD. Round to the nearest tenth, if necessary.

Answer 1

http://media.education2020.com/evresources/2004-04-01-01-00_files/i0140000.jpg

Answer 2

using AC and BC, what is AB?

Answer 3

i dont know, 18? @jim_thompson5910

Answer 4

are you familiar with the pythagorean theorem?

Answer 5

sort of

Answer 6

it's the formula

a^2 + b^2 = c^2

where 'a' and 'b' are the legs of a right triangle, c is the hypotenuse

Answer 7

compare the triangle I just drew to the triangle you have for your problem

Answer 8

you'll see that

a = unknown
b = 18
c = 36

Answer 9

18 square root 3?

Answer 10

very good

Answer 11

now it turns out that there are 3 triangles in your picture

they are:

triangle ABC, which is the biggest triangle (B is the right angle)
triangle ADB, where D is the right angle
triangle BDC, where D is the right angle

we'll focus on triangles ABC and ADB

why? Because we know AB, AC and BC, it makes sense to use ABC. We want to find AD, so that's why we're using triangle ADB

Answer 12

If we focus on triangle ABC, we see that AC is the hypotenuse

If we turn our attention to triangle ADB, we'll find that AB is the hypotenuse

So they are corresponding parts

Answer 13

AD is the longer leg of triangle ADB

AB is the longer leg of triangle ABC

so this is another pair of corresponding parts

Answer 14

we then divide the corresponding parts of ABC over ADB (in the same order) like this

AC/AB = AB/AD

then plug in the info we know

36/(18*sqrt(3)) = (18*sqrt(3))/AD

and then solve for AD

Answer 15

and what would be the answer?

Answer 16

were you able to solve for AD?

Answer 17

no

Answer 18

cross multiply to get

36*AD = (18*sqrt(3))(18*sqrt(3))

36*AD = 18*18*sqrt(3)*sqrt(3)

36*AD = 18^2*(sqrt(3))^2

36*AD = 324*3

36*AD = 972

I'll let you finish

Answer 19

i dont understand what you are doing and what sqrt is

Answer 20

sqrt stands for "square root"

Answer 21

okay and what would the answer be?

Answer 22

look back at my steps and finish up solving for AD

Answer 23

@jim_thompson5910 im on this question right now can you help me? pls