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If angle B measures 25^circ what is the approximate perimeter of the triangle below? 10.3 units 11.8 units 22.1 units 25.2 units

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If angle B measures 25^circ  what is the approximate perimeter of the triangle below?
10.3 units
11.8 units
22.1 units
25.2 units

If angle B measures 25^circ what is the approximate perimeter of the triangle below? 10.3 units 11.8 units 22.1 units 25.2 units

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NeilMaster · Tutor for 5 years

Answer

To find the perimeter of the right triangle ABC, we need to find the lengths of all three sides: AB, BC, and AC. We already know that AB = 4 units and that ∠A is a right angle, which means that ∠C is \(90^{\circ} - 25^{\circ} = 65^{\circ}\).Step 1: Find the length of AC (the adjacent side to ∠B) using the cosine function.\[\cos(B) = \frac{adjacent}{hypotenuse}\]\[\cos(25^{\circ}) = \frac{AB}{AC}\]\[AC = \frac{AB}{\cos(25^{\circ})}\]\[AC = \frac{4}{\cos(25^{\circ})}\]Using a calculator, we find that:\[\cos(25^{\circ}) \approx 0.9063\]\[AC \approx \frac{4}{0.9063}\]\[AC \approx 4.4142 \text{ units}\]Step 2: Find the length of BC (the opposite side to ∠B) using the sine function.\[\sin(B) = \frac{opposite}{hypotenuse}\]\[\sin(25^{\circ}) = \frac{BC}{AC}\]\[BC = AC \cdot \sin(25^{\circ})\]\[BC = 4.4142 \cdot \sin(25^{\circ})\]Using a calculator, we find that:\[\sin(25^{\circ}) \approx 0.4226\]\[BC \approx 4.4142 \cdot 0.4226\]\[BC \approx 1.8651 \text{ units}\]Step 3: Calculate the perimeter by adding the lengths of all three sides.\[\text{Perimeter} = AB + AC + BC\]\[\text{Perimeter} \approx 4 + 4.4142 + 1.8651\]\[\text{Perimeter} \approx 10.2793 \text{ units}\]The closest answer to our calculation is 10.3 units, so the approximate perimeter of the triangle is:Answer: 10.3 units
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