There are several ways to find the length of the third side of an acute triangle, depending on the information given about the triangle and the sides. Some common methods include:
Using the Pythagorean theorem: If you have a right triangle, you can use the Pythagorean theorem to find the length of the third side. The theorem states that the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides.
Using the Law of Cosines: If you know the lengths of two sides and the measure of the angle between them, you can use the law of cosines to find the length of the third side.
Using the Law of Sines: If you know the lengths of two sides and the measure of the angle opposite one of them, you can use the law of sines to find the length of the third side.
It's important to note that you need to know at least 2 sides and an angle or the side opposite to the right angle (if the triangle is a right triangle) in order to find the length of the third side.