Question

Find bc. Round the answer to the nearest tenth.

Answer 1

Is BC=2.3 one of the options?

For that question, you can use the cosine rule, where;

`{a}^(2) = {b}^(2) + {c}^(2) - 2(b)(c) \cos( \alpha )`
In this case, we have..

`{bc}^(2) = {1.8}^(2) + {2.1}^(2) - 2(1.8)(2.1) \cos(70)`
Solving for BC with this will get you 2.250406, rounded off to the tenth is 2.3.

Answer 2

BC = 2.3

Explanation:

Given : A triangle With side AB = 1.8 , AC = 2.1 and angle = 70 degree.

To find : Find BC .

Solution : We have given

AB = 1.8 , AC = 2.1

Angle = 70 degree.

By the cosine rule : The third side of a triangle when we know two sides and the angle between them.

BC² = AB² + AC² − 2AB(AC) cos(A).

Plug the values AB = 1.8 , AC = 2.1

BC² = (1.8)² + (2.1)² − 2(1.8)(2.1)cos(70)

BC² = 3.24 + 4.41 - 7.56 ( 0.34).

BC² = 3.24 + 4.41 - 2.5704

BC² = 5.0796.

Taking square root

BC = √ 5.0796.

BC = 2.25

Nearest tenth = 2.3

Therefore, BC = 2.3