# How to find an angle using law of cosines

## How do you find the cosine of an angle with a calculator?

Press the “Cos” button, generally found in the middle of the calculator. “Cos” is short for cosine. Your calculator should display “cos(.” Enter the measure of the angle you want to know the cosine ratio of.

## On which triangle can the law of cosines be applied once to find an unknown angle measure?

In which c is the side across from angle C. Remember that the Law of Cosines works for any triangle, not just right triangles.

## How do you solve for cosine?

In any right angled triangle, for any angle:

1. The sine of the angle = the length of the opposite side. the length of the hypotenuse.
2. The cosine of the angle = the length of the adjacent side. the length of the hypotenuse.
3. The tangent of the angle = the length of the opposite side. the length of the adjacent side.

## How do you find an angle with 3 sides?

To solve an SSS triangle:

1. use The Law of Cosines first to calculate one of the angles.
2. then use The Law of Cosines again to find another angle.
3. and finally use angles of a triangle add to 180° to find the last angle.

## How do you find the degree of cosine?

You can convert radians into degrees by multiplying it with 180/Math. PI , Furthermore the inverse cosine (or cos^-1 like some textbooks denote this) is the Math. acos method ( a standing for arc ). double AB = 125; double AC = 150; double angleA = Math.

## How do you find the angle of a triangle given two sides?

Find the angle of elevation of the plane from point A on the ground.

1. Step 1 The two sides we know are Opposite (300) and Adjacent (400).
2. Step 2 SOHCAHTOA tells us we must use Tangent.
3. Step 3 Calculate Opposite/Adjacent = 300/400 = 0.75.
4. Step 4 Find the angle from your calculator using tan-1
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## How do you solve a triangle with two sides and one angle?

“SAS” is when we know two sides and the angle between them. use The Law of Cosines to calculate the unknown side, then use The Law of Sines to find the smaller of the other two angles, and then use the three angles add to 180° to find the last angle.

## Does law of cosines work for all triangles?

It works on any triangle, not just right triangles. where a and b are the two given sides, C is their included angle, and c is the unknown third side. See figure above.

## What is the formula for sin cos and tan?

Sine, Cosine and TangentSine Function:sin(θ) = Opposite / HypotenuseCosine Function:cos(θ) = Adjacent / HypotenuseTangent Function:tan(θ) = Opposite / Adjacent

## What is the cosine law equation?

The cosine of a right angle is 0, so the law of cosines, c2 = a2 + b2 – 2ab cos C, simplifies to becomes the Pythagorean identity, c2 = a2 + b2, for right triangles which we know is valid.

## How do you find the size of an angle?

Divide that known length by the sine of its opposite angle. If the length measures six inches divide six by 0.574 to get 10.45. Find the sine of the angle opposite to the unknown length. If this angle is, for instance, 80 degrees: sin (40) = 0.643.