Always, Sometimes Or Never !
Always-
Squares have two diagonals that meet at a right angle- because a square has 4 equal angles.
Sometimes-
A hexagon has six equal length sides- because if the hexagon is irregular then sometimes the sides are not equal.
Always-
A cuboid has 2 square faces -because a cuboid is made of 2 square faces and 4 rectangular faces.
Sometimes
Triangles have a line of symmetry- because if you have an irregular triangle then it doesn’t have a line symmetry.
Always-
Cutting a corner off a square makes a pentagon- because cutting of a corner adds a new line.
Sometimes-
The base of a pyramid is a square- because you can have pyramids with different bases as well.
Sometimes-
Quadrilaterals can be cut into two equal triangles-because if you cut quadrilateral that has 4 even angles diagonally in half you get 2 equal triangles.
Sometimes-
The number of lines of symmetry in a regular shapes is equal to the number of sides- because a square has 4 sides and 4 lines of symmetry but a circle has 1 side and lots of lines of symmetry.
Sometimes-
Triangles tessellate- because if you put Equilateral, isosceles or right angle triangles together they all fit with no gaps.
Always-
When you cut off a piece from a 2D shape you reduce the area and perimeter- because cutting a piece off is reducing the perimeter.