## geerky42 How to find the exact value of $$\cos\left(\dfrac{\pi}{7}\right)$$? one year ago one year ago

pi/7 ?

2. geerky42

Yes.

3. geerky42

Is it possible to find the exactly value algebraically?

4. starbot

yes it is possible but I'm not quite sure how

5. Ephilo

try using the half angle formula

6. geerky42

@Ephilo How?