i am facing a problem since i nvr since this type of equation before to solve it

when i solve until this part which is

500sin(theta) - 866.03cos(theta) - 693.82 = 0

in order to solve the (theta), even thought i divide by cos (theta), i still have 693.82 / cos (theta)

how shud i solve it?

thank you if u would like to lend a hand for me