Answer:

Step-by-step explanation:
The Law of Cosines is given as:
.
Plugging in given values, we get:
.
1/2 or 0.5 x 3/4 or 0.75 = 0.375 or 3/8
the rest I dont' understand what you wrote, is it a subtraction or a negative?
2/3 is way bigger then 1/4
You can calculate the difference between the bars by counting the lines inbetween.