Express cos^2 x in terms of cos2x. hence, express f(x) = 6cos^2 x - 4sin 2x in the form r cos (2x + y degrees) + p where r, y and p are constants. find the maxium and minimum values of f(x) and sketch its graph in the domain -180 < = x < = 360

Answer asap and if you do you will get brainliest. catherine buys a gallon of ice cream from the store. after taking it home, she eats a fifth of a gallon of ice cream. her sister eats some of the ice cream as well. if two-thirds of the original amount of ice cream is left, then what fraction of a gallon of ice cream did her sister eat?