need help on 'angle between two straight lines' question (1 Viewer)

[frippyful]

hi guys.
i really need help on this question. i have tried it and tried many similar questions (triangular) and i just can not seem to get a single angle right. i will give you the answer to check, but could you also please inform me of what you pressed on your calculator to get the degrees, e.g. shift tan, or just tan, i don't know.

find the angles to the nearest degree, of the triangles formed by the lines joining the given verticies A, B, C.
A(2,9) B(44,1) C(-3,-2)

thanks so much in advance for your efforts!

 

[Carrotsticks]

1. Can you write down the formula that you are using? Maybe you are using the wrong one. Many people get the sign wrong with the angle between two lines formula.

2. Is your calculator in degree mode?

 

[frippyful]

I'm using the gradient formula and the tan theta formula. i don't know how to use symbols on here so i will try my best to state the formula (just keep an open mind)
tan theta = the absolute value of m1-m2/1+m1xm2

i hope you know what formula I'm talking about. can you please help me?

 

[Carrotsticks]

I think I know what you mean, I did the question about three times and kept obtaining different values. Combination of arithmetic errors and typing it incorrectly into the calculator. You have some very nasty values there.

I'll try it again tomorrow when I'm a bit more fresh, unless somebody here does it for you.

 

[AAEldar]

Are they right?

 

[Carrotsticks]

Are they right?

Try doing the question by doing the inverse tan three times, then again by doing it twice and using C = 180 - (A + B)

I did that and got different answers, so I was very

 

[AAEldar]

Try doing the question by doing the inverse tan three times, then again by doing it twice and using C = 180 - (A + B)

I did that and got different answers, so I was very

I didn't use the angle between two lines formula, I found the distance between each point and constructed a triangle and then used the cosine rule to find the angle.

 

[math man]

sorry in advance carrot

 

[math man]

Are they right?

correct

 

[Carrotsticks]

View attachment 24387
sorry in advance carrot

Actually Math Man, the diagram is much prettier than the one you drew beforehand for that locus question

I found my mistake. My calculator lags a bit when you type in fractions within fractions etc.

When I was trying to type 11, it lagged and since I pressed it too quickly, it registered as only 1, so the whole time I was typing 1/5 instead of 11/5.

 

[math man]

yay carrot approves of my shitty paint diagrams

 

[Carrotsticks]

A challenger appears!

I actually had this diagram ages ago haha, but I kept on making silly errors when typing it out in my calculator, so I never posted it thinking I may have made some sort of arithmetic error.