Answer:
130.1°
Step-by-step explanation:
Using the cosine rule:
[tex] = { \cos }^{ - 1} ( \frac{ {14}^{2} + {19}^{2} - {30}^{2} }{2 \times 14 \times 19} )[/tex]
= 130.146°
The measure of angle is 72.8° (accurate to one decimal place ) between the 14 cm and 19 cm sides.
The Law of Cosines (also called the Cosine Rule) is defined as it relates all three sides of a triangle with an angle of a triangle.
c² = a² + b² − 2ab cos(C)
The cosine rule, also known as the law of cosines, relates all 3 sides of a triangle with an angle of a triangle. it relates the lengths of the sides of a triangle to the cosine of one of its angles.
Given data as :
Length of side a = 14 cm
Length of side b = 19 cm
Length of side c = 20 cm
The angle of C is the between the side a and side b
According to the cosine rule,
c² = a² + b² − 2ab cos(C)
Substitute the values of a, b and c in the Cosine Rule,
20² = 14² + 19² - 2(14)(19)cos(C)
400 = 196 + 361 - 532cos(C)
400 = 557 - 532cos(C)
532cos(C) = 557 - 400
532cos(C) = 157
cos(C) = 157/532
cos(C) = 0.2951
(C) = cos⁻¹(0.2951)
(C) = 72.83
(C) = 72.8° (accurate to one decimal place)
Hence, the measure of angle is 72.8° (accurate to one decimal place ) between the 14 cm and 19 cm sides.
Learn more about Cosine Rule here:
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