2007-01-11 09:23:55 · 5 answers · asked by EMP 2 in Science & Mathematics ➔ Mathematics
It's used for absolutely nothing. It *almost* looks like the cosine formula in trigonometry, though, except it's missing a + sign between b^2 and c^2.
a^2 = b^2 + c^2 - 2bc cosA
a, b, and c represent sides of a triangle opposite to angles A, B, and C respectively. This formula is best used when given no angles but given all the sides.
2007-01-11 09:30:14 · answer #1 · answered by Puggy 7 · 1⤊ 0⤋
a^2=b^2c^2-2bcCos A This should be
a^2 = b^2 + c^2 -2bcCos A
It is the law of cosines and is used to solve a triangle if you know two sides of the triangle and the angle they form.
2007-01-11 09:34:22 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
I think you mean, a^2 = b^2 + c^2 - 2bc cos A, adding a plus-sign.
This is the Law of Cosines, and used to solve triangles given the three sides (SSS) or two sides and an included angle (SAS), and certain cases of two sides and an excluded angle, namely where the side opposite the angle is longer (SsA).
HTH.
2007-01-11 09:32:06 · answer #3 · answered by Anonymous · 0⤊ 0⤋
It's the law of cosines & is used in trig. if you know all 3 sides of a triangle, you can use it to find angles. If you have SAS, you can use it to find the 3rd side & then the other angles can be found with the law of sines.
2007-01-11 09:36:24 · answer #4 · answered by yupchagee 7 · 0⤊ 0⤋
It's used for triangles that are not right triangles.
It's a relationship between the sides: a,b,c and the angle A which opposes side a.
2007-01-11 09:31:05 · answer #5 · answered by modulo_function 7 · 0⤊ 0⤋