∥ the character of parallelism.

⧧ want of parallelism.

≚ equiangular, or similar.

⫨ equilateral.

▱ rhomboid.

◠ concentrix.

○ circle.

∟ right angle.

∫ integration, (summa or sum).

° denotes a degree: thus, 45° implies 45 degrees.