Ticks into Equations
Part of the Triangles section of Coddy's Geometry journey. Lesson 4 of 63.
Tick marks are facts you can calculate with. If two sides carry the same ticks they are equal, so their labels are equal too. When a label holds a letter, that gives you an equation.
Here QR and RP carry one tick each, so 2x + 1 = 13. Take away 1 and divide by 2: x = 6. Check it: 2 × 6 + 1 = 13. The unticked side, 10, plays no part.
On the board the figure sits on the paper. Tap the two ticked sides, pick the rule Marked equal sides, and the board writes the equation as your own line. Then solve it with the moves, as in Algebra.
Challenge
Two sides of this triangle are ticked equal. Tap them, pick the rule that connects them, and solve the equation the board writes for x.
Then press Check.
Try it yourself
Use the figure to find x
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 Leg