Question

Cos19pie/6 x Cos 17pie/6 - Cos 11pie/6 x cos 13pie/6

Answer 1

Answer:

0

Step-by-step explanation:

since

cos19π/6xcos17π/6-cos11π/6cos13π/6

=cos(π+π/6)xcos(π-π/6)-cos(-π/6)xcos(π/6)

= -√3/2(-√3/2)-(√3/2)(√3/2)

3/4-3/4=0if you didn't understand how cos19π/6 is cos(π+π/6)

you can just subtract 2π from 19π/6

i.e19π/6-2π ( since trigonometric functions are periodic after every2π)

it comes out to be 7π/6 or 210°

which is 180°+30°or π+π/6

similarly I have simplified the cos functions and expressed them in a form that also tells us which quadrant they belong to and also what theta they operate on.

therefore we get the answer to be 0 in the end.

hope you understand now. if not I am here to help.