Processing Math: Done

From Förberedande kurs i matematik 1

Using the unit circle shows that the equation cos3x=−12  has two solutions for 03x2,

3x=2+4=43and3x=+4=45.

We obtain the other solutions by adding multiples of 2,

3x=43+2nand3x=45+2n

i.e.

x=4+32nandx=125+32n

where n is an arbitrary integer.