Answer:
All rhombi are parallelograms.
All squares are rhombi.
No trapezoid is a rectangle.
1. The answer would be about 20.72, or 20.7142 if you don’t want the rounded version
2. The answer is -12.8
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
Answer:
C. The trails are not independent.
5 9/10 .........................................