Final: Three Sticks
Part of the Triangles section of Coddy's Geometry journey. Lesson 59 of 63.
A craft kit has two rods, 9 cm and 15 cm long, and a third rod that you cut to length. The third rod's length in centimetres is 3x - 3, where x is the setting on the cutting guide. For the three rods to make a triangle, the third must fit the range the other two allow.
Find every setting x that gives a real triangle.
Challenge
On the blank sheet, write the range the third rod, 3x - 3, must lie in beside rods of 9 and 15. Then solve it for x and press Check.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis 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 ReachingThe Range of the Third SideThe FormulaRecap: The Third Side5The Pythagorean Theorem
Squares on the SidesFinding the HypotenusePythagorean TriplesWhen It Is Not WholeRecap: The Hypotenuse3Perimeter
Around the EdgeA Missing SideIsosceles PerimeterSides as ExpressionsRecap: Around the Edge6Finding a Leg
Working BackwardsThe LadderWhich Side Is c?A Leg That Is Not WholeRecap: Finding a Leg9Similar Triangles
Same Shape, Different SizeThe Scale FactorFinding a SideMatching the CornersRecap: Similar Triangles12Final Challenges
Final: Three SticksFinal: The FenceFinal: The LadderFinal: The ShadowFinal: Master of Triangles