Complete the identity. sin^4x - cos^4x = ?

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

Write the expression in simplified radical form. show all steps and work including any foil method work. (hint: use the conjugate. no decimal answers.) (9-2√3)/(12+√3)

Divide. write in simplest form 41/6 divided by 10