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Answer:
We use cosine rule also called cosine law which states
c^2=a^2+b^2-2abcosC
given
a=8cm, b=7cm, c=9cm cos C?
9^2=8^+7^2-2*8*7 cos C
expand
81=64+49-112 cos C
like terms together
81-113=-112 cos C
-32=-112cos C
multiply both sides by -1
32=112cos C
divide both sides by 112
32/112=cos C
cosC=0.2857
find cos inverse of 0.2857
angle C= 73.40
The answer is 38.8 repeating. Might as well just round it
Okie doke. So, we are rounding this number to the nearest thousandths place, which is three digits behind the decimal. The rules for rounding are if the number is 5 or more in the digit behind it, the number goes up. If it is 4 or less, the number goes back. In other words, we depend on the digit right of the digit we are rounding to in order to see what we do. The number we are rounding is 1.49882. The 8 is in the thousandths place and the 8 is to the right of that, which is the ten thousandths place. Because 8 is greater than 5, the number rounds up. So the number rounded to the nearest thousandth is 1.500.
