Lesson 10.1: Sings of Comparison: Approximately Equal To, Similar To, Congruent To
Approximately equals sign
When comparing quantities, the values may be nearly equal, but are not exactly equal or identical. Since it would be erroneous to show the comparison with the parallel lines of an equals sign, the print symbol for approximately equals consists of parallel wavy lines, double tilde. The braille symbol for approximately equals, dot four dots one five six dot four dots one five six, resembles its print equivalent. It uses the symbol for tilde, but in a vertical rather than horizontal configuration.
≈ approximately equal to
Similar to sign, tilde
If the measures of respective angles are equal and the measures of respective sides are in the same proportion, then geometric figures are considered to be mathematically similar. The print symbol for similar to consists of a single wavy line, tilde. The braille symbol for similar to is dot four dots one five six.
∼ similar to
Congruent to sign
When two figures are similar and the measures of their respective sides are equal, then the figures are considered to be congruent. Both the print and braille symbols combine the symbol for similarity with the symbol for equality. In print, the tilde appears above the equals sign. The braille sign for congruent to is dot four dots one five six dots four six dots one three.
≅ congruent to
one point seven eight is approximately equal to one point eight
pi is approximately equal to three point one four
triangle A B C is similar to triangle X Y Z
trapezoid A B C D is similar to trapezoid M N O P
triangle A B C is congruent to triangle X Y Z
segment A B is congruent to segment C D
angle A is congruent to angle B