# Can you use sine and cosine law on right triangles?

The

**Sine Rule can**be used in any**triangle**(not just**right**-angled**triangles**) where a side and its opposite angle are known.**You will**only ever need two parts of the**Sine Rule**formula, not all three.**You will**need to know at least**one**pair of a side with its opposite angle to**use**the**Sine Rule**.A.

### Is the law of cosines only for right triangles?

Yet trigonometry—a subject whose rules are generally based on

**right triangles**—can still be used to solve a non-**right triangle**. You need different tools, though. Enter the**laws**of sines and**cosines**. In an oblique**triangle**, there are six unknowns: the three angle measures and the three side lengths.#### How do you find the lengths of a triangle?

In this right**triangle**, you are given the measurements for the hypotenuse, c, and one leg, b. The hypotenuse is always opposite the right angle and it is always the longest side of the**triangle**. To find the**length**of leg a, substitute the known values into the Pythagorean Theorem.#### What is the law of cosines?

**Law**of**Cosines**. The**law**of**cosines**for calculating one side of a triangle when the angle opposite and the other two sides are known. Click on the highlighted text for either side c or angle C to initiate calculation.#### What is the law of sines used for?

In trigonometry, the**law of sines**,**sine law**,**sine**formula, or**sine**rule is an equation relating the lengths of the sides of a triangle (any shape) to the**sines**of its angles. It can also be**used when**two sides and one of the non-enclosed angles are known.

B.

### Do sin cos and tan only work with right triangles?

The trigonometric functions are based on a measure of 90 degrees yes, but it is not restricted to

**work**with**only right triangles**. You can use**sine**and**cosine**laws when the**triangle**isn't a**right triangle**.#### Can you use the law of sines on a right triangle?

The**Law of Sines**says that in any given**triangle**, the ratio of any side length to the**sine**of its opposite angle is the same for all three sides of the**triangle**. This is true for any**triangle**, not just**right triangles**. Press 'reset' in the diagram above.#### How do you find the angles of a triangle?

"SSS" is when we know three**sides**of the triangle, and want to**find**the missing**angles**. To solve an SSS triangle: use The Law of Cosines first to calculate one of the**angles**. then use The Law of Cosines again to**find**another angle.#### How do you do law of sines?

The**Law of Sines**is the relationship between the sides and angles of non-right (oblique) triangles . Simply, it states that the ratio of the length of a side of a triangle to the**sine**of the angle opposite that side is the same for all sides and angles in a given triangle.

Updated: 3rd September 2018