Math  /  Geometry

QuestionA painter is going to apply a special coating to a triangular metal plate on a new building. Two sides measure 12.3 cm and 16.4 cm . She knows that the angle between the two sides is 116116^{\circ}. What is the area of the surface she plans to cover with the coating?
The surface area is \square cm2\mathrm{cm}^{2} (Simplify your answer. Type an integer or a decimal. Round to the nearest tenth as needed.)

Studdy Solution

STEP 1

What is this asking? We need to find the area of a triangle given two sides and the angle between them. Watch out! Make sure your calculator is in degree mode, not radians!
Also, remember that the area formula uses the *sine* of the angle, not the cosine or tangent.

STEP 2

1. Set up the Area Formula
2. Calculate the Area

STEP 3

The area of a triangle given two sides aa and bb and the included angle CC is given by: A=12absin(C) A = \frac{1}{2} \cdot a \cdot b \cdot \sin(C) This formula is *super* handy when you have this specific information about a triangle.
It's like a shortcut to the area!

STEP 4

In our problem, we have a=12.3a = 12.3 cm, b=16.4b = 16.4 cm, and C=116C = 116^{\circ}.
Let's plug these values into our awesome formula: A=1212.316.4sin(116) A = \frac{1}{2} \cdot 12.3 \cdot 16.4 \cdot \sin(116^{\circ}) See how nicely everything fits?
We're almost there!

STEP 5

First, let's find the sine of the angle.
Make sure your calculator is in degree mode! sin(116)0.8988 \sin(116^{\circ}) \approx \mathbf{0.8988} Keep this value handy; we'll use it in the next step.

STEP 6

Now, we can multiply everything together: A=1212.316.40.8988 A = \frac{1}{2} \cdot 12.3 \cdot 16.4 \cdot \mathbf{0.8988} A12201.720.8988 A \approx \frac{1}{2} \cdot 201.72 \cdot \mathbf{0.8988} A100.860.8988 A \approx 100.86 \cdot \mathbf{0.8988} A90.6312 A \approx \mathbf{90.6312} So, the area is approximately 90.6312\mathbf{90.6312} cm2\text{cm}^2.

STEP 7

The problem asks us to round to the nearest tenth.
Looking at our result, the tenths place is 66, and the next digit is 33, which is less than 55.
So we round down: A90.6 A \approx \mathbf{90.6}

STEP 8

The area of the triangular metal plate is approximately 90.6\mathbf{90.6} cm2\text{cm}^2.

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