Question

Difficulty: MediumBasic Trigonometric Ratios, Special Angles, and Identities

In a right-angled triangle PQRPQR, where Q=90\angle Q = 90^\circ and tanP=512\tan P = \frac{5}{12}, what is the exact value of sinP+cosP\sin P + \cos P?

  1. 1713\frac{17}{13}Answer
  2. B
    713\frac{7}{13}
  3. C
    1712\frac{17}{12}
  4. D
    125\frac{12}{5}

Answer

1713\frac{17}{13}
Using tanP=512\tan P = \frac{5}{12}, the triangle has opposite side 55, adjacent side 1212, and hypotenuse 52+122=13\sqrt{5^2+12^2} = 13. Therefore, sinP=513\sin P = \frac{5}{13} and cosP=1213\cos P = \frac{12}{13}, giving a sum of 1713\frac{17}{13}.

Step-by-Step Solution

1
Identify the side lengths of the right triangle PQRPQR using the given tangent ratio.
Opposite side to P=5P = 5, adjacent side to P=12P = 12.
By definition, tanP=OppositeAdjacent=512\tan P = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{5}{12}.
2
Calculate the length of the hypotenuse PRPR using the Pythagorean theorem.
Hypotenuse PR=52+122=25+144=169=13PR = \sqrt{5^2 + 12^2} = \sqrt{25 + 144} = \sqrt{169} = 13.
In a right triangle, hypotenuse2=opposite2+adjacent2\text{hypotenuse}^2 = \text{opposite}^2 + \text{adjacent}^2.
3
Determine sinP\sin P and cosP\cos P and compute their sum.
sinP=513\sin P = \frac{5}{13}, cosP=1213\cos P = \frac{12}{13}, so sinP+cosP=513+1213=1713\sin P + \cos P = \frac{5}{13} + \frac{12}{13} = \frac{17}{13}.
sinP=OppositeHypotenuse\sin P = \frac{\text{Opposite}}{\text{Hypotenuse}} and cosP=AdjacentHypotenuse\cos P = \frac{\text{Adjacent}}{\text{Hypotenuse}}.

Key Concept

Basic Trigonometric Ratios and Pythagorean Triples
Estimated Time:1m 30s
Rate this question