2007-11-15 05:45:17 · 13 answers · asked by Lydia 3 in Science & Mathematics ➔ Mathematics
none of the angles are 90%%D
2007-11-15 05:48:56 · update #1
is it valad to rework the equation to:
cosA=(b^2+c^2)-a^2/(-2bc)
2007-11-15 07:44:06 · update #2
Thanks for all your help. For those of you who said to measure it, live is not always that easy :)
2007-11-19 01:24:50 · update #3
Not a t all...
Regards
Tonio
2007-11-15 05:47:36 · answer #1 · answered by Bertrando 4 · 0⤊ 2⤋
There is something called cosine theorem, that establish that, if a, b and c are the sides of a triangle and alpha is the angle between b and c, then
a^2 = b^2 + c^2 -2 b*c*cos(alpha)
If you know a, b and c, this is an equation for alpha:
alpha = arccos((b^2+c^2-a^2)/(2bc))
and by interchanging the sides you would obtain the other two angles:
beta = arccos((a^2+c^2-b^2)/(2ac))
gamma = arccos((a^2+b^2-c^2)/(2ab))
2007-11-15 13:55:40 · answer #2 · answered by GusBsAs 6 · 1⤊ 0⤋
If you know all the sides of triangle, then apply cosine rule
a^2 = b^2 + c^2 - 2bccos(A)
you can find out angle A, as you know all other parameters side
a, b and c
then apply sine rule
a/sinA = b/sinB = c/sinC
from this you can find out other two angles B and C
2007-11-15 13:52:36 · answer #3 · answered by mohanrao d 7 · 4⤊ 0⤋
Answer to your problem is rightly given by Mr Mohan Rao D. There is one more way to find out angles. Just construct the triangle to the largest possible scale. And measure the required angles.
2007-11-16 21:09:27 · answer #4 · answered by Pramod Kumar 7 · 0⤊ 1⤋
are you a drafter? how did you know that %%d means the degree sign? just curious...
can you break the triangle up to make a right angle within the larger triangle? making one of the shorter sides one side of the right angle and the longer side a portion of the hypotenuse? then...you can find the one angle, and work from there...
2007-11-15 13:51:13 · answer #5 · answered by jbe 2 · 0⤊ 0⤋
Yes. Use the law of cosines.
c^2 =a^2 +b^2 -2abcos x, where a,b,c, are the three sides and x is the angle opposite side c.
So just solve for x.
2007-11-15 14:30:00 · answer #6 · answered by ironduke8159 7 · 1⤊ 0⤋
Yes there is a way....
you use sine rule
a /(sin A) = b/(sin B) = c/(sinC)
a,b,c are the lengths of the triangle and A,B,C are the angles...
2007-11-15 13:53:08 · answer #7 · answered by Ziah X 1 · 0⤊ 2⤋
you have to use the rule of cosines to find one of the angles. Then you can use the rule of sines to find the others.
2007-11-15 13:53:36 · answer #8 · answered by Anonymous · 1⤊ 0⤋
Trigonometry?
2007-11-15 13:52:42 · answer #9 · answered by Anonymous · 0⤊ 2⤋
u can use a protector for measuring it.
2007-11-15 19:17:16 · answer #10 · answered by se 1 · 0⤊ 1⤋