Question

Anyone need help?

Answer 1

yesss

Answer 2

with Law of Cosines;

The law of cosines is a formula that relates the three sides of a triangle to the cosine of a given angle. This formula allows you
Case I) to calculate the side length of non-right triangle as long as you know two sides and an angle (See picture below)
Case 2) to calculate any angle of a triangle if you know all three side lengths

and emilyashbury you need help with?

Answer 3

A road construction company charges 125 million dollars for constructing a 20km stretch of highway and 245 million dollars for constructing 40 km of similar highway. Based on these costs and assuming a linear relationship exists between the total cost and the length of road constructed, determine the cost constructing: a) 25 km of similar highway, b) 52km of similar highway

Answer 4

It's B. Company charges 125 million dollars for constructing a 20km stretch of highway and 245 million dollars for constructing 40 km or similar highway add 20+40 get 245m and then take away the 2 from 245mill therefore it's 52km. which is answer B

Answer 5

no, thats not the question :/ it's asking to determine how much money it costs to build 25km and 52 km @timanti

Answer 6

oh okay, so 125 for 20km, and 245 for 40km so basically what its doing is adding 125mill to each 20 it skips. So we need to figure out how much will it add for 25, can you do that? @EmilyAshbury

Answer 7

hello? :)

Answer 8

i don't get it @timanti

Answer 9

okay. so for 20 added, it adds on 125mill. Let's estimate how much for 25km. it's about 130mill. or it's exactly on that.

Answer 10

the answer page says 25km is 155million and 52km is 317million, but i just don't know how to do it

Answer 11

oh so i guess it was wrong then.. So adding on 5 is exactly 35. okay and 52km is 317mill. Let's figure this out

Answer 12

hmm. i'm not sure about this

Answer 13

Setup a system of equations.

Answer 14

i guess mathbrz will help you sorry i couldnt

Answer 15

Since they are linear equations, you know your 1st eq is:

\[125,000,000 = m(20) + b\]

and 2nd is

\[245,000,000 = m(40) + b\]

Answer 16

thank you for trying:) @timanti

Answer 17

what do i do after :/ @mathbrz

Answer 18

Solve the 1st equation for m, and plug that substitution into the 2nd equation, and solve for b.

\[\frac{125000000-b}{20} = m \]

Answer 19

plug that into the 2nd equation

\[245,000,000 = (\frac{125,000,000-b}{20})(40) + b\]

Answer 20

Solve for b.

Answer 21

your welcome

Answer 22

here, b = 5,000,000

Answer 23

Now, plug b=5,000,000 into your equation solving for m,

that is

\[m = \frac{125,000,000 - 5,000,000}{20}\], m = 6,000,000

Answer 24

Now you now your m and b, so you can make new equations to solve for 25 km and 52 km

cost = m(x) + b

cost = 6,000,000(x) + 5,000,000

Answer 25

plug in 25 km and 52 km and solve for cost

Answer 26

get it?

Answer 27

Each equation of a line in this problem has a common slope M, and common y-intercept B

Answer 28

So your first step was to find the common slope and y-intercept, and then form your equation and plug in x

Answer 29

"EmilyAshbury
Medals 0

the answer page says 25km is 155million and 52km is 317million, but i just don't know how to do it"

you will find that plugging in 25 and 52 into the equation we built is correct

Answer 30

Thank you so much!! @mathbrz

Answer 31

yw :)

Answer 32

@timanti the law of consines is awesome. better than pythag

Answer 33

actually equivalent to pythag because cos(90) = cos (pi/2) = 0 which negates the extra part of the formula

Answer 34

ohhh

Answer 35

cool huh? they should stop teaching pythag and only teach law of cos starting in HS

Answer 36

i know right?

Answer 37

well im gonna close this Q bye!!

Answer 38

cya have a nice evening