you must know more information. Like the lengths of 2 sides. Then using Trig (law of sines or law of cosines) you can find the remaining sides and angles.
The answer depends on what the problem is: are you required to find the lengths of the missing sides, the area, angles, length of diagonal, or WHAT!
Add together the lengths of the four sides; or add the lengths of the two different sides and then double it.
That really depends what else you know about the triangle. For example, if you only know the lengths of two sides, you simply don't have enough information.
Find the perimeter by adding the lengths of the sides
you must know more information. Like the lengths of 2 sides. Then using Trig (law of sines or law of cosines) you can find the remaining sides and angles.
Surely you know how to find the third side of a right triangle, when you know the lengths of the other two. Find it, and then add up the lengths of the three sides to get the perimeter.
The answer depends on what the problem is: are you required to find the lengths of the missing sides, the area, angles, length of diagonal, or WHAT!
In order to find the perimeter of a 3D rectangle you must gather the lengths of the known sides, calculate the missing rectangular values, and use the formula for perimeter.
Add together the lengths of the four sides; or add the lengths of the two different sides and then double it.
That really depends what else you know about the triangle. For example, if you only know the lengths of two sides, you simply don't have enough information.
It depends on which side is missing. If the hypotenuse (longest side, opposite right angle) is missing, square the lengths of the other two sides, add them, and then square root your answer. If a leg is missing, square the two remaining sides, subtract the smaller from the larger, and square root it. All of this is derived from the Pythagorean Theorem: a^2+b^2=c^2, where a and b are the lengths of the two legs and c is the length of the hypotenuse.
If you know the lengths of two sides then use Pythagoras' theorem to find the third side.
Find the perimeter by adding the lengths of the sides
You add the lengths of all the sides. If the sides happen to be of equal length, you multiply this length by 7.
Add the lengths of the four sides
Which side lengths? To calculate the parallel sides, you need the height of the trapezium and one of the sides, and you substitute them into the formula: h(a + b)/2, where h = height, a and b are the parallel side lengths. If you want to find the sides that are not parallel, you need the parallel sides, as well as the height of the trapezium. Then, by using Pythagoras theorem, with the side length the hypotenuse, you can find their lengths.