1. Given any triangle ABC with sides BC=a, AC=b and AB=c, the following are true :
i) the larger the angle, the larger the side in front of it, and the other way around as well. (Sine Law) Let a=20 in, then the largest angle is angle A.
ii) Given the measures of the sides of a triangle. Then the cosines of any of the angles can be found by the following formula:

2.

3. m(A) = Arccos(-0.641)≈130°,
4. Remark: We calculate Arccos with a scientific calculator or computer software unless it is one of the well known values, ex Arccos(0.5)=60°, Arccos(-0.5)=120° etc
C. 60%
The probability that a person surveyed is 40 or older and gets the news by reading the paper is 60%.
Step-by-step explanation:
In our case, we have to find the probability of a person getting their news by reading the paper. But we are given with a condition that the person must be 40 or older.
The survey is conducted among 80 people.
Number of people aged 40 or older = 40
No of people aged 40 or older and read paper = 24
Probability formula is the ratio of number of favorable outcomes to the total number of possible outcomes.
Probability of a person aged 40 or older reads a paper =
(No. of People aged 40 or older and read paper)/(No. of people aged 40 or older)
= 24/40
= 0.6
= 60%
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