Answer:
The equations should have been added up to equal 180 instead of being set to equal each other. The two are supplementary angles, which can be seen due the rule that a pair of interior angles on the same side of the transversal is supplementary. To fix this issue from the work that they did, they should subtract the 140 from 180, so the correct measure of DKH is actually 40 degrees.
Step-by-step explanation:
25 - 5x = 80
+ 5x + 5x
25 = 5x + 80
- 80 -80
-55 = 5x
-55/5 = 11
x = 11
Hope I helped!
Let me know if you need anything else!
~ Zoe
Given:
cos 120°
To find:
The exact value of cos 120° in simplest form with a rational denominator.
Solution:
We have,
It can be written as
Therefore, the exact value of cos 120° is .