what do you get when you plug in -61776 into cos^-1(x) on your calc? how come i keep getting error domain????

Question

asnaseer · Answer

the cosine of an angle varies between 1 and -1.
so it can never have the value -61776

zepp · Answer

This ^ :(

zepp · Answer

I should type a little bit faster..

asnaseer · Answer

you are asking your calculator to find the angle whose cosine would be -61776 - no such angle exists

asnaseer · Answer

sorry zepp - didn't mean to step on your toes :)

anonymous · Answer

ok so im trying to find the largest angle when given sides 22,36, and 44 using cosC= a^2 + b^2  - c^2 / 2 ab

asnaseer · Answer

kalloohkallay32: you must have made an error in your calculations

zepp · Answer

The largest side is faced to the hypontenuse, and I didn't getting any error.

zepp · Answer

didn't get*

asnaseer · Answer

zepp: the largest angle would indeed be opposite the largest side. but, in this case, we do not have a right-angled triangle, so it is not the hypotenuse.

anonymous · Answer

common error... use parenthesis when entering in your calculator...

cosC= (a^2 + b^2  - c^2 )/ (2 ab)
so C = cos^-1 (a^2 + b^2  - c^2 )/ (2 ab)

asnaseer · Answer

kalloohkallay32: make sure you do the division right in your calculator. you should be calculating:$$\cos(C)=\frac{a^2+b^2-c^2}{2ab}$$

zepp · Answer

Oh yeah right, thx asnaseer :D

zepp · Answer

According to my calculator, the largest angle should be 87.17747 degrees.