Question

I need help with pre calculus.

Answer 1

Answer:

  a) a = 7.37, b = 15.13, C = 67°

  b) 1 triangle

Step-by-step explanation:

a)

Two angles and one side are given. That means the triangle is uniquely determined, and the remaining sides can be found from the Law of Sines.

The third angle is ...

  C = 180° -A -B = 180° -29° -84° = 67°

Then the Law of Sines tells you ...

  a/sin(A) = b/sin(B) = c/sin(C)

  a = sin(A)/sin(C)·c = sin(29°)/sin(67°)·14 ≈ 7.37

  b = sin(B)/sin(C)·c = sin(84°)/sin(67°)·14 ≈ 15.13

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b)

Ordinarily, when the given angle (B = 30°) is opposite the shorter of the given sides (b = 10 < a = 20), it means there are two possible solutions to the triangle.

However, when the sine of the angle is exactly equal to the ratio of the given sides: sin(30°) = 10/20 = 1/2, the larger angle can only be 90°. That is, the one triangle that can be formed is a right triangle.

The Law of Sines tells you this.

  sin(A)/a = sin(B)/b

  sin(A) = (a/b)sin(B) . . . . . . multiply by 'a'

  A = arcsin(a/b·sin(B)) = arcsin(20/10·sin(π/6)) = arcsin(1)

  A = 90°