Answer: 20
Step-by-step explanation:
Let 's complete our quadrilateral to a rectangle ; and subtract from it the area highlighted in red

Answer:
= 9
Step-by-step explanation:
Given that,
Asn expression : 
We need to evaluate the above expression.
We know that, 
So,

or

So, the value of
is 9. Hence, the correct option is (b).
In this problem, you apply principles in trigonometry. Since it is not mentioned, you will not assume that the triangle is a special triangle such as the right triangle. Hence, you cannot use Pythagorean formulas. The only equations you can use is the Law of Sines and Law of Cosines.
For finding side a, you can answer this easily by the Law of Cosines. The equation is
a2=b2 +c2 -2bccosA
a2 = 11^2 + 8^2 -2(11)(8)(cos54)
a2 = 81.55
a = √81.55
a = 9
Then, we use the Law of Sines to find angles B and C. The formula would be
a/sinA = b/sinB = c/sinC
9/sin54° = 11/sinB
B = 80.4°
9/sin54° = 8/sinC
C = 45.6°
The answer would be: a ≈ 9, C ≈ 45.6, B ≈ 80.4
Step-by-step explanation: