cos ( − 30° ) =
 A.  \(\large \boldsymbol{-\;\frac 12} \)
B.    \(\large \boldsymbol{\;\frac 12} \)
C.    \(\large \boldsymbol{\;\frac {\sqrt 3}2} \)
D.  \(\large \boldsymbol{-\;\;\frac {\sqrt 3}2} \)
E.  \(\large \boldsymbol{-\;\;\frac {\sqrt 3}3} \)
A    B    C    D    E

[ 4-2145 - op net sinds 23.10.99-(E)-20.7.2024 ]

Translation in   E N G L I S H

cos ( − 30° )   = A.   \(\boldsymbol{-\;\frac 12} \)
B.    \(\boldsymbol{\;\frac 12} \)
C.    \(\boldsymbol{\;\frac {\sqrt 3}2} \)
D.   \(\boldsymbol{-\;\;\frac {\sqrt 3}2} \)
E.   \( \boldsymbol{-\;\;\frac {\sqrt 3}3} \)

Oplossing - Solution

Tegengestelde hoeken hebben dezelfde cosinus.
Dat betekent dat je in  cos (− 30°)  het minteken gewoon mag weglaten !
Dus  cos (− 30°) = cos 30° = v3/2
gricha