P

• Paranormal triangles (1 C, 9 P)
• Pyramids (6 C, 16 P)

T

• Triangular tilings (19 P)
• Triangle geometry (7 C, 40 P)
• Triangles named after people (22 P)
• Triangles of numbers (28 P)
• Triangular buildings (1 C, 23 P)
• Types of triangles (22 P)

• Triangle
• List of triangle topics

0–9

• 5-Con triangles

A

• Accident triangle
• Area of a triangle

B

• Black triangle (badge)
• Brocard triangle

D

• Dragon's Eye (symbol)

E

• Eye of Providence

G

• Gore (fabrics)
• Gusset

H

• Hart circle
• Hess triangle

I

• Illusory contour
• Ireland's Vanishing Triangle

K

• Källén function
• Karpman drama triangle
• Kobon triangle problem

L

• Lapel pin

P

• Penrose triangle
• Pink triangle
• Purple triangle

R

• Red triangle (badge)
• Red triangle
• Red triangle (Palestinian symbol)
• Research Triangle

S

• Similarity system of triangles
• Sliver triangle
• Spidron

T

• Ternary plot
• Texas Triangle
• Tortoises with Triangle and Time
• Triangle of opposition
• Triangular number

U

• Ukrainian Death Triangle

V

• Valknut

W

• Watlington White Mark