Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11
Advertisement Remove all ads

Find the Values of the Following Trigonometric Ratio: Cos 19 π 4 - Mathematics

Find the values of the following trigonometric ratio:

\[\cos\frac{19\pi}{4}\]
Advertisement Remove all ads

Solution

We have: 

\[\cos\frac{19\pi}{4} = \cos 855^\circ\]

\[855^\circ = 90^\circ \times 9 + 45^\circ\]

\[855^\circ\text{ lies in the second quadrant in which the cosine function is negative . }\]

Also, 9 is an odd integer .

\[ \therefore \cos\left( 855^\circ \right) = \cos\left( 90^\circ \times 9 + 45^\circ \right) = - \sin\left( 45^\circ \right) = - \frac{1}{\sqrt{2}}\]

Concept: Negative Function Or Trigonometric Functions of Negative Angles
  Is there an error in this question or solution?
Advertisement Remove all ads

APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 5 Trigonometric Functions
Exercise 5.3 | Q 1.11 | Page 39
Advertisement Remove all ads
Advertisement Remove all ads
Share
Notifications

View all notifications


      Forgot password?
View in app×