Hello, so i was doing some math assigment and i am stuck i have just cos(-alpha) and i can't tell if it is +cos or -cos. I usually have things like cos(180+alpha) etc?. Created by Vladimir. science-mathematics-en - mathematics-en

Remember simple rules.cos(a)= cos(-a)= cos(2pi-a)cos(a+-pi)= -cos(a)

How much is cos(-alpha)?

May 2021 3 62 Report

How much is cos(-alpha)?

Hello, so i was doing some math assigment and i am stuck i have just cos(-alpha) and i can't tell if it is +cos or -cos. I usually have things like cos(180+alpha) etc?

Science & Mathematics / Mathematics

kumorifox

cos(-alpha) = cos(alpha)

For sin and tan, the function would generate the negative value. If you look at the unit circle, you can see why. Take 60° as an example. +60° is in the first quadrant, where everything is positive, thus, cos 60 is positive. -60° is in the 4th quadrant, where cos is positive. Thus, cos(-60) will be positive.