how do you know if you have a right triangle by using 3,4, and 5?

Answer 1

3^2+4^2=5^2

Answer 2

The Theorem of Pythagoras applies only to the special case of right triangles. Therefore, if the sum of the squares of two sides of a triangle equals the square of the longest side, the angle opposite the longest side is a right angle, and you have a right triangle:
3^2 + 4^2 =?5^2
9 + 16 = 25,
so you have a right triangle.

With Trigonometry, you can apply the more general Law of Cosines:
c^2 = a^2 + b^2 - 2abcosC
solving for C,
C = arccos((a^2 + b^2 - c^2)/(2ab))
C = arccos((9 + 16 - 25)/(2*3*4))
C = arccos(0)
C = 90°

Answer 3

Well, a^2 + b^2 = c^2 in a right triangle, right?

So, does 3^2 + 4^2 = 5^2 ?

9 + 16 = 25 ?

25 = 25

Answer 4

3 squared + 4 squared = 5 squared
9 + 16 = 25

Answer 5

Do you mean how do you use these numbers to see if you have a right triangle, ie., one with a 90 degree angle? If so start at the angle and measure 3 inches along one leg and 4 inches on the other and mark these points. Then measure the distance between those two points. If they are 5 inches apart, it is a right angle.

Answer 6

The formula for a right triangle: A squared + B squared = C squared or, in this case, 9 + 16 = 25.

Answer 7

You use the pythagorean theorem.
3^2 + 4^2 = 25
25 = 5^2
In other words
a^2 + b^2 = c^2
Also, keep in mind that c must be the largest of the three sides you are checking.

Answer 8

see if 3 squared + 4 squared equals 5 squared (pythagorean check)

Answer 9

You just know these things.