pythagorus i can work out. an irregular triangle how can you work out the lengths of the sides. a sine rule? or cosine rule ? i do not understand these. any help appreciated
2007-11-25 05:47:30 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
S.oh C.ah T.oa
ring any bells?
2007-11-25 05:54:46 · answer #1 · answered by Anonymous · 0⤊ 3⤋
You need to be given the length of one side, and and two angles or two sides and the included angle.
Law of cosines is c^2 = a^2+b^2 -2abcos x, where a and b are the two given sides and x is the angle they include.
Law of sines is a/ sin A =b/sinB = c/sinC, where A,B, and C are the angtles opposite sides a,b, c respectively.
2007-11-25 13:56:54 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
If you know the length of all the sides and nothing else you cn easily find it's area using Herons formula.When you have the area you can go on quite easily to find the perpendicular height from each side and from that all other angles.
Take a triangle with sides of length a, b and c.
Herons formula states that the area(A)is given by:-
A =square root of(s(s-a)(s-b)(s-c)) where s=(a+b+c)/2
2007-11-25 14:11:31 · answer #3 · answered by L D 6 · 0⤊ 0⤋
Law of sines is one way:
sin(A)/a = sin(B)/c = sin(C)/c
A, B, and C are the angles opposite sides a, b, and c, respectively.
Law of cosines is another way:
c² = a² + b² - 2ab cos(C)
where a, b, and c are sides and C is the angle opposite side c.
.
2007-11-25 13:55:30 · answer #4 · answered by Robert L 7 · 0⤊ 0⤋
YES.
http://www.bbc.co.uk/schools/gcsebitesize/maths/shapeh/areaofatrianglerev3.shtml
2007-11-25 13:56:52 · answer #5 · answered by Pauline 7 · 0⤊ 0⤋