What’s on the Triangle Theorems poster
The rule, 4 worked examples.
- These relationships hold for every triangle, whatever its shape.
- angles sum to 180°
- Angle sum = 180°
- Exterior angle = = sum of the two remote interior angles
- Isosceles = base angles equal
- Triangle inequality = a + b > c
The midsegment joining two midpoints is parallel to the third side and exactly half its length.
Questions about the Triangle Theorems poster
- What’s on the Triangle Theorems poster?
- The rule, 4 worked examples. These relationships hold for every triangle, whatever its shape.; angles sum to 180°; Angle sum = 180°; Exterior angle = = sum of the two remote interior angles; Isosceles = base angles equal; Triangle inequality = a + b > c. The midsegment joining two midpoints is parallel to the third side and exactly half its length.
- Who is the Triangle Theorems poster for?
- Triangle Theorems is filed under 9th Grade (ages 14–15), so it matches what that year asks a child to remember. It is equally useful to an older student revisiting math, and to the parent or teacher answering the question at the kitchen table.
- When should you use the Triangle Theorems poster?
- Fill in every angle you can deduce. One usually unlocks the next. A wall chart earns its place by being glanceable from where the work is happening, so Triangle Theorems belongs on the wall where that math work actually happens, within glancing distance, rather than filed away.
- What other posters go with Triangle Theorems?
- Similar Triangles, Absolute Value Equations and Arithmetic Sequences sit alongside Triangle Theorems in the 9th Grade set. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Similar TrianglesAbsolute Value EquationsArithmetic Sequences
- Is the Triangle Theorems poster free to download and print?
- Yes. Triangle Theorems downloads as a free PDF with no account, no email and no watermark, like everything else in the 9th Grade set. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Triangle Theorems poster print at?
- Triangle Theorems is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Triangle Theorems loses nothing.Printing guide
Related posters
Charts that sit alongside Triangle Theorems on the same wall.
Browse every 9th Grade poster, or start from the full catalogue.