Krishna
0

Step 1:  Note down the given important points

EXAMPLE:  \cos 7A = \sin (A - 6\degree)

7A is an acute angle

Step 2: Write the equivalent complementary angle

NOTE:   \cos \theta = \sin (90\degree - \theta)

EXAMPLE:   \cos 7A = \sin (90\degree - 7A) ........(1)

Step 3:  Substitute the calculated value and simplify

EXAMPLE:   \sin (90\degree - 7A) = \sin (A - 6\degree)

90\degree - 7A = A - 6\degree

8A = 96\degree

A =\frac{96}{8}

A = 12\degree