# trigonometry

posted by .

This is an outline that i have to use to find the solution of the question. It involves logarithms and half-angle formulas.I have worked though it but got stuck on some parts. I'd like if you look over my work.

solve the triangle for which given parts are
a=27 ,b=21 ,c=24

Now i used the cosine law and got the answers

A=73 deg 23' 55"
B=48 deg 11' 23"
C=58 deg 24' 43"

...................
okay now for this outline;

a=27
b=21
c=25
----
2s=73
s=36.5
s-a=9.5
s-b=15
s-c=11.5
log(s-a)= .97772
log(s-b)=1.19033
log(s-c)=1.06070
--------
=3.22875
log s =1.56229
--------
2)1.66646
--------
log r =0.83323

now this part I'm having trouble with.

log r = 0.83323
log(s-a) = 0.97772
--------
log tan A/2 = 9.85551 - 10
A = ? << can you help me convert.

log r = 0.83323
log (s-b) = 1.19033
--------
log tan B/2 = 9.64290 - 10
B = ? same here my brain freezes

log r = 0.83323
log (s-c) = 1.06070
--------
log tan C/2 = 9.77253 - 10
C = ?

A+B+C= 180 deg 0' 2"

do they match?

• trigonometry -

I noticed an error in your outline
log(s-b) = log 15 = 1.17609 you have 1.19033

Your outline suggests to me Heron's formula for finding the area of a triangle.

then I see log r =0.83323
where does r come from ?

To do a calculation like
log tan A/2 = 9.85551 - 10
A = ?

http://www.jiskha.com/display.cgi?id=1298862691

• trigonometry -

that was a typo its 15.5 which makes the log entry correct.

=3.22875
log s =1.56229 subtract.
--------
2)1.66646 <<.. then divide by 2 =
--------
log r =0.83323

the reason why i posted the out line was because they did not match. and i didn't understand how you got the inverse tangent .

## Similar Questions

1. ### MATH

1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL STEPS) sin 2x - sin x = 0 2.) GIVEN: sin u = 3/5, 0 < u < ï/2 Find the exact values of: sin 2u, cos 2u and tan 2u using the double-angle formulas. 3.)Use …
2. ### Math

I am stuck on a problem that has to do with the double angle formulas. I have to solve this: 4sinxcosx = 1. I tried using the formula 2sinu = 2sinucosu by substituting it in like this: 2(2sinxcosx)= 1 but then I am stuck
3. ### trigonometry

okay so i have this trigonometry problem were i HAVE to use logarithms. Now this is my work but can u help me solve it using logarithms. Find the area of the following triangles:(use logarithms) 1) c=426, A=45degrees 48' 36",and B=61degrees …
4. ### trigonometry

1. Finde the area of the following tringles: (use Logarithms) A) a=12.7, b=21.5, c=28.6. i'm not of the answer i got. i got 127.6 if you got something different can you show me how you did while using logarithms.
5. ### Trigonometry (Logarthims)

Give checks to the following two questions Use logarithms and the law of tangents to solve the triangle ABC, given that a=21.46 ft, b=46.28 ft, and C=32°28'30" without logarithms i can do this problem easily and i have. but when i …
6. ### trigonometry

Use logarithms and the law of tangents to solve the triangle ABC, given that a=21.46 ft, b=46.28 ft, and C=32°28'30" Also Give checks. I know the use of logarithms is unnecessary but i have to show my solution by using logarithms …
7. ### trigonometry (repost) Mathmate

I want to start by saying thank you . You have no idea how much u have helped me understand logarithms, even better then the books i have (it poorly explains the subject of trigonometry let alone logarithms and antilog). Your last …
8. ### Trigonometry /Logarithms (brace yourself)

This is an outline that i have to use to find the solution of the question. It involves logarithms and half-angle formulas.I have worked though it but got stuck on some parts. I'd like if you look over my work. solve the triangle for …
9. ### trigonometry repost .

This is an outline that i have to use to find the solution of the question. It involves logarithms and half-angle formulas.I have worked though it but got stuck on some parts. I'd like if you look over my work. solve the triangle for …
10. ### Math-Trigonometry

Use the half-angle formulas to find the exact values. Cosine 165 degrees, Sine 157 degrees 30' and tan pi/8

More Similar Questions