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the cosine rule is derived from the division of the adjacent side & hypotenuse

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Q: How is the cosine rule derived?
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Related questions

How does one differentiate between the sine rule and the cosine rule?

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.


Who invented the cosine rule?

It was invented sometim but if you find out put it on here! Love Megan


What proportion do you use to find the length of the third side triangle XYZ?

The answer depends on the information that you have: it could be the sine rule or the cosine rule.


Is it is necessary to be a right angle triangle to use sine 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.


How are all three versions of the law of cosines correct?

It follows from the cyclical symmetry of the cosine rule.


How do you find a measurement of an angle in a triangle when you only know the side length?

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.


What is cosine cubed?

It is cosine*cosine*cosine.


CosA equals a2 plus c2 minus b2 by 2ac what is this formula?

This is known as the Cosine Rule.


What are the interior angles to 1 decimal place of a scalene triangle with sides 12 cm 14 cm and 16 cm showing work?

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)


What is the formula for calculating the central angle given chord length and radius?

You can use the cosine rule to calculate the central angle.


An isoceles triangle has two sides of 52 and one side of 40 What are the angles?

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


How does euler's formula work?

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