Question

Which measurement of acute triangle ABC can you find by direct substitution of the labeled measures in the Law of Cosines?

Answer 1

@MARC_D

Answer 2

Mark How Could You ;-;

Answer 3

cosine rule:\[A^2=B^2+C^2-2(B)(C)Cos \angle\]

Answer 4

i dont understand

Answer 5

\[AC^2=8^2+3^2-2(8)(3)Cos57.53\]

Answer 6

which part u don't understand?

Answer 7

how we are getting the answer

Answer 8

i dont understand how you got formulas for these

Answer 9

This is the formula u got to remember which is the cosine rule

Answer 10

okay

Answer 11

for example,

Answer 12

i dont understand

Answer 13

but i dont think its asking for that

Answer 14

In order to find the value of C,u must use the cosine rule formula which it,

Answer 15

i'm just giving an example to u :)

Answer 16

okay :) thank you

Answer 17

okay,back to the example..cosine rule formula(u will hv to memorise,no shortcut):\[A^2=B^2+C^2-2(B)(C)Cos~\angle\]look at the attached file

Answer 18

okay

Answer 19

alright,i will give u another question same as that to solve it..

Answer 20

okay

Answer 21

Find the value of length A..

Answer 22

This is how u should do..\[A^2=B^2+C^2-2(B)(C)Cos~\angle\]\[A^2=9^2+7^2-2(9)(7)Cos~60\]

Answer 23

i still dont understand

Answer 24

okay,tell me which part u don't understand?

Answer 25

i get lost with solving formulas

Answer 26

i dont understand how to come up with the answer

Answer 27

okay,lets start from the scratch..

Answer 28

This is the formula that u hv to memorise which is the cosine rule formula:\[A^2=B^2+C^2-2(B)(C)Cos~\angle\] look at the attached file given

Answer 29

For example,find the value of length A..(Look at the attached file)

Answer 30

u r given that length of B=9 and C=7 and also the angle a which is 60 degree..Our goal is to find the length of A

Answer 31

so would you use SAS

Answer 32

SAS?

Answer 33

side angle side

Answer 34

yep,that's is right! :)

Answer 35

use the cosine rule formula\[A^2=B^2+C^2-2(B)(C)Cos~\angle\]

Answer 36

it will look like this\[A^2=9^2+7^2-2(9)(7)Cos60\]

Answer 37

now how do i solve that

Answer 38

U will hv to do like this\[A^2=81+49-126\cos60\]

Answer 39

use ur calculator to calculate the value

Answer 40

i dont have one

Answer 41

u will get\[A^2=130-63\]

Answer 42

\[A^2=67\]

Answer 43

is that the answer to a

Answer 44

\[A=\sqrt{67}\]

Answer 45

yes

Answer 46

oh okay

Answer 47

Therefore,the length of A is\[A=8.19\]

Answer 48

okay

Answer 49

so how do we find the answer to my problem

Answer 50

okay,back to ur original question

Answer 51

Our goal is to find the length of AC..

Answer 52

Use the example i gave u just now n apply it on ur question..

Answer 53

remember the SAS

Answer 54

:)

Answer 55

but i dont understand how you get the answers i sent you

Answer 56

ermm,which part u don't get it?

Answer 57

because there are no numbers in the answers

Answer 58

nonono,u don't get what i mean..
i mean that use the same concept i thought the previous example n try to apply the same concept on ur question :)

Answer 59

*taught u

Answer 60

i understand that but im lost because i dont know what its asking for
and i dont understand the letters at the bottom

Answer 61

im still not comprehending

Answer 62

Let show u how to do..
Step 1: use the cosine rule formula\[A^2=B^2+C^2-2(B)(C)Cos~\angle\]

Answer 63

ok

Answer 64

Step 2: Substitute the value into the formula\[A^2=8^2+3^2-2(8)(3)Cos~B\]

Answer 65

ok

Answer 66

Ok,as u can see that A is AC

Answer 67

N the value of angle i substitute is angle B

Answer 68

So,it would look like this\[AC^2=8^2+3^2-2(8)(3)CosB\]

Answer 69

so its the first one

Answer 70

yes,that's right! :)

Answer 71

option B and C is wrong bcoz we didn't substitute the angle a or angle c

Answer 72

Therefore,the answer is A

Answer 73

i have one more question if you have time

Answer 74

i can understand if you want to leave though

Answer 75

It's already 3.00 am in the morning for me..xD
I need to n get some rest...maybe tmrw i will be back again..

Answer 76

okay thank you for your time im sorry if i gave you a really bad headache to

Answer 77

It's okay.. :)
Cya next time..bye!