Question

Lucy started the proof of the law of cosines using triangle WXY as shown.

Answer 1

The step which contains the first error in calculation is: B. Step 2 - the sine ratio was applied incorrectly.

What is the law of sines?

The law of sines is also referred to as sine law or sine rule and it can be defined as an equation that relates the side lengths of a triangle to the sines of its angles.

Mathematically, the law of sines is given by this equation:

$\frac{sinA}{a} =\frac{sinB}{b}$

For any right-angled triangle, the ratio of the length of its opposite sides to the length of its hypotenuse is generally referred to as sine ratio. Thus, sine ratio is given by this formula:

cos(θ) = Opp/Hyp

Where:

• Opp is the opposite side of a right-angled triangle.

• Hyp is the hypotenuse of a right-angled triangle.

• θ is the angle.

In this context, we can infer and logically deduce that the step which contains the first error in calculation is step 2:

sin(W) = y/XZ; XZsin(W) = y.

In conclusion, the correct step should have been written as follows:

sin(W) = XZ/y; ysin(W) = XZ.

Read more on law of sines here: brainly.com/question/27868305

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