Question

Hello Brainliacs !

Q: i) Why
$cos(\pi - \alpha ) = - \cos( \alpha )$

ii) Why is "cos" negative over here ?

Answer 1

The cos is negative because it shows a change in direction or the direction is in negative way.

Suppose the - 20 is given on the number then.
- cos (20) the negative sign is taken outside to make the angle and the number correctly significant so, as to, Mark a direction to the left side and the negativity is eliminated.

There is another reason and that is on the basis of quadrants in the all silver tea cups ASTC.

so by seeing this it transmits to the 4th quadrant of tan as it is negative. But, the cos and sin are positive. So, the negative equity is often taken out of the bracket.

Answer 2

heya answer is here......

cos(pi-alpha)=cosalpha......

● y bcz from the all silver tea cups formula we can get
negative of cos.....
● but in trignametry says...for cos and sec are havent negative values and there not satisfied the all values means in any solution....
● actually there dont have negative values ....we r studied from 10th class and inter graduation......


i know this much.....may be it will help u frnd....if not report it.....