A Leg That Is Not Whole
Part of the Triangles section of Coddy's Geometry journey. Lesson 38 of 71.
A leg can come out as a root, just as a hypotenuse can. With hypotenuse 7 and leg 2:
Hypotenuse 7, leg 2
a = √(7^2 - 2^2) = √(45)
a = 3√(5)
45 has the square factor 9, so the root simplifies to 3√(5). 3√(5) is about 6.7, which is a little less than the hypotenuse 7, as a leg must be.
When the number under the root has no square factor, the root is the finished answer. Hypotenuse 6 and leg 1 give √(35). The rules for roots from the hypotenuse chapter are the same here. The only difference is that the squares are subtracted instead of added.
Challenge
A right triangle has hypotenuse 8 and one leg 3.
Find the other leg b exactly.
Try it yourself
Solve for b
This lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Triangles
1Sides and Names
Three Sides, Three CornersSorting by SidesNaming by AnglesTicks into EquationsThe Longest SideRecap: Sorting Triangles2The Triangle Inequality
Can Three Sticks Meet?Exactly ReachingHow Short Can It Be?How Long Can It Be?The Range of the Third SideThe FormulaWhole-Number SidesRecap: The Third Side5The Hypotenuse
Squares on the SidesFinding the HypotenusePythagorean TriplesWhen It Is Not WholeSimplifying the RootRecap: The Hypotenuse8Special Right Triangles
The 45-45-90 TriangleLegs from the HypotenuseThe 30-60-90 TriangleAll Three SidesWhich Triangle Is It?Recap: Special Triangles11Mixing Area and Pythagoras
Height of an IsoscelesArea from the HeightThe Equilateral TriangleRight Triangle PerimeterRecap: Two Tools3Perimeter
Around the EdgeA Missing SideIsosceles PerimeterEquilateral PerimeterSides as ExpressionsWrite the PerimeterRecap: Around the Edge6Finding a Leg
Working BackwardsThe LadderWhich Side Is c?A Leg That Is Not WholeRecap: Finding a Leg