What is the approximate value of tan b..a. 0.92. b. 0.40
..c.0.44. d. 2.29

The grass is not green; the grass is green.
Geometry is interesting; geometry is not interesting.
This rose is not white; this rose is white.
Two points determine a line; two points do not determine a line.
5+4≠90; 5+4=90.
All pigs are fat; all pigs are not fat.
Milk does not taste good; milk tastes good.
A line has no length; a line has length.
My dog has fleas; my dog doesn't have fleas.
A line does not have a midpoint; a line does have a midpoint.

To negate a statement, you make it mean the opposite thing.