prove cos(x)= 15/17

Solution

prove

cos (x) = \frac{15}{17}

False

Solution steps

cos (x) = \frac{15}{17}

Show that the two sides are not equal

For

cos (x) = \frac{15}{17}

plug in

x = 0

cos (0) = 1

cos (0)

Use the following trivial identity:

cos (0) = 1

cos (0)

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= 1

= 1

The two sides are not equal

\Rightarrow False

tan (b) + cot (b) = \frac{1}{sin ( b ) cos ( b )}

csc (A) - sin (A) = (cos (A)) (cot (A))

\frac{cos ^{2} ( x )}{cos ^{2} ( x )} = 1

\frac{( tan ( x ) cot ( x ) )}{sec ( x )} = cos (x)

sec (b) cot (b) = csc (b) tan (b)