Question

Tan(2x + 10derajat) = cot(3x - 15derajat)
berapa x nya?

Answer 1

sin (2x+10) sin (3x-15) = cos (3x-15) cos (2x+10)

1/2 [- cos (2x+10+3x-15) + cos (2x+10-3x+15)] = 1/2 [ cos (2x+10+3x-15) + cos (2x+10-3x+15) ]

- cos (5x-5) + cos (-x+25) = cos (5x-5) + cos (-x+25)
                 
   - cos (5x-5) = cos (5x-5)
  2 cos (5x-5) = 0
     cos (5x-5) = 0
     cos (5x-5) = cos 90
            5x-5 = 90
               5x = 95
                 x = 19