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30 votes
30 votes
Solve ABC where ∠C = 90°, a = 15 cm, and b = 7 cm.

User Rajkumar Singh
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1 Answer

11 votes
11 votes

Answer:

c ≈ 16.55cm ; ∠A = 65 degrees ; ∠B = 25 degrees

Explanation:

Because of the Pythagorean theorem, we can solve for c.

This theorem states: a^2 + b^2 = c^2

Since there can only be 180 degrees in a triangle, angle C must be our largest angle. This means that side c is our hypotenuse (the longest side).

Using all of this information, we can say that 15^2 + 7^2 = c^2.

Simplifying that equation, we get that 274 = c^2.

In order to find c, we must square root both sides, and we find that c is about 16.55 cm long.

Using SOHCAHTOA, we know that the tan(∠B)=
(7)/(15). Therefore, the arctan (
(7)/(15)) = ∠B.

Once you find that ∠B is about 25 degrees, you can add ∠B and ∠C together and subtract that from 180 to find ∠A.

∠A = 65 degrees.

User APEALED
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