Question

Find the value of b. Round the nearest tenth.

Answer 1

Answer:

b= sin(43°) * 8 / sin(55°) ≈ 6.7

Step-by-step explanation:

Regarding the law of sines, each angle corresponds to the side opposite of it. Here, that means that the 82 degree angle is opposite of side c (so they correspond) and that the 55 degree angle corresponds to the side with 8cm. However, we are trying to find the length of side b. Therefore, assuming that the side with 8cm is side A, if we know that

sin A / a = sinB/b = sin C / C

= sin(55°)/8 = sinB/b = sin(82°) / c, we can take c out of the equation to get

sin(55°)/8 = sinB/b

If we know sinB, we can multiply both sides by 8 to remove a denominator to get

sin(55°) * b / 8 = sinB

multiply both sides by 8 to remove the other denominator to get

sin(55°) * b = sinB * 8

divide both sides by sin(55°) to isolate the b

b = sinB * 8/sin(55°).

Therefore, if we know sinB, we can figure out the length of b.

Because the angles of a triangle add up to 180 degrees, we can say that

180 = 82 + 55 + angle B

180 = 137 + B

subtract both sides by 137 to isolate B

43 = B

b= sin(43°) * 8 / sin(55°) ≈ 6.7