Looking for HSC notes and resources? Check out our Notes & Resources page

trigonometric identity question need help (1 Viewer)

Thread starter Thatstudentm9
Start date May 17, 2017

T

Thatstudentm9

Member

May 17, 2017

#1

question : 2cos^2 30 ° -1

J

$$\noindent Using the double angle expansion (that $\cos 2 \theta = 2 \cos^2 \theta -1), \\ $ the expression simplifies to $\cos \left ( 2\times 30 \right )= \cos 60 = \frac{1}{2} \\ \\ $If you haven't learnt double angles yet, then use the absolute values of trig ratios to simplify $\\ 2 \cos ^2 30 -1 = 2\left ( \frac{\sqrt{3}}{2} \right )^{2}-1\\ = 2\times \frac{3}{4}-1 = \frac{1}{2}$

You must log in or register to reply here.

Share:

Facebook Twitter Reddit Pinterest Tumblr WhatsApp Email Link

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top

trigonometric identity question need help (1 Viewer)

Thatstudentm9

Member

jathu123

Active Member

Users Who Are Viewing This Thread (Users: 0, Guests: 1)