The answer depends on the information that you have: it could be the sine rule or the cosine rule.
No. Sine rule (and cosine rule) apply to all triangles in Euclidean space (plane geometry). A simplification occurs when there is a right angle because the sine of the right angle is 1 and the cosine is 0. Thus you get Pythagoras theorem for right triangles.
It follows from the cyclical symmetry of the cosine rule.
This is known as the Cosine Rule.
Let the sides be a, b and c and their opposite angles be A, B and C Using the cosine rule angle A = 75.5 degrees Using the cosine rule angle B = 57.9 degrees Angle C muct be 46.6 degrees because there are 180 degrees in a triangle Cosine Rule: cos A = (b2+c2-a2)/(2*b*c)
The sine rule is a comparison of ratios: (sin A)/a = (sin B)/b = (sin C)/c. The cosine rule looks similar to the theorem of Pythagoras: c2 = a2 + b2 - 2ab cos C.
It was invented sometim but if you find out put it on here! Love Megan
The answer depends on the information that you have: it could be the sine rule or the cosine rule.
No. Sine rule (and cosine rule) apply to all triangles in Euclidean space (plane geometry). A simplification occurs when there is a right angle because the sine of the right angle is 1 and the cosine is 0. Thus you get Pythagoras theorem for right triangles.
It follows from the cyclical symmetry of the cosine rule.
If you do not know only a side length you cannot. If you know all three side lengths then you can use the cosine rule. You can continue using the cosine rule for the other two angles but, once you have one angle, it is simpler to use the sine rule.
It is cosine*cosine*cosine.
This is known as the Cosine Rule.
Let the sides be a, b and c and their opposite angles be A, B and C Using the cosine rule angle A = 75.5 degrees Using the cosine rule angle B = 57.9 degrees Angle C muct be 46.6 degrees because there are 180 degrees in a triangle Cosine Rule: cos A = (b2+c2-a2)/(2*b*c)
You can use the cosine rule to calculate the central angle.
Let the sides be abc and their opposite angles be ABC and so: Using the cosine rule angle A = 67.38 degrees Using the cosine rule angle B = 67.38 degrees Angle C: 180-67.38-67.38 = 45.24 degrees
It can be derived from the series expansion for the sine, the cosine, and the exponential function. More details here: http://en.wikipedia.org/wiki/Euler's_formula#Using_power_series