(sin^2 a - cos^2 b )/( cos^2 a - cos^2 b ) = cot (a + b) / tan (a - b)

Is the square root of 4 plus the square root of 16 rational?

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

What is the maximum of the sinusoidal function