Prove this

1-tan^2x/1+tan^2x=cos^2x-sin^2x

The given dot plot represents the average daily temperatures, in degrees fahrenheit, recorded in a town during the first 15 days of september. if the dot plot is converted to a box plot, the first quartile would be drawn at , ( 59,60,61,62) and the third quartile would be drawn at . (61,62,63,64)