Without using trignometery tables find value of, cos70/sin20+cos57. cosec33 - 2cos60

Here is some thoughts on this:

cos 57 = sin (90-57) = sin 33

so cos 57. cosec 33 = cos 57 / sin 33 = sin 33 / sin33 = 1

2 cos 60 = 2 * 1/2 = 1

so the last 2 parts work out to 0

now we have to find cos 70 / sin 20

sin 20 = cos 70 so this comes to 1

so finally the answer is 1