Answer:
Step-by-step explanation:
21)
The sine rule is expressed as
a/SinA = b/SinB = c/SinC
Where a, b and c are the length of each side of the triangle and angle A, Angle B and angle C are the corresponding angles of the triangle. Therefore,
12/Sin 64 = x/Sin 12
Cross multiplying, it becomes
xSin 64 = 12Sin12
xSin 64 = 12 × 0.209
0.8988x = 2.508
x = 2.508/0.8988
x = 2.79
The sum of the angles in a triangle is 180 degrees. Therefore, the unknown angle in triangle is
180 - (64 + 12) = 104 degrees. Therefore,
y/Sin104 = 12/Sin64
ySin64 = 12Sin104
0.8988y = 12 × 0.9703 = 11.6436
y = 11.6436/0.8988
y = 12.95
22) we would apply the law of Cosines which is expressed as
a² = b² + c² - 2bcCosA
Therefore,
28² = 20² + 24² - 2 × 20 × 24Cosx
784 = 400 + 576 - 960Cosx
784 = 976 - 960Cosx
960Cosx = 976 - 784 = 192
Cosx = 192/960 = 0.2
x = Cos^(-1)0.2
x = 78.5°
