Question

1. In triangle PQR, =31.7°, QR=0.81cm, right angle is at the middle letter. Find PR?

Answer 1

Answer:

The length of side PR is 0.95 cm.

Step-by-step explanation:

The triangle PQR is shown below:

According to the trigonometric ratios:  

$cos \theta =\frac{Base}{Hypotenuse}$

Compute the value of PR as follows:

$cos \theta =\frac{Base}{Hypotenuse} \\cos R =\frac{QR}{PR}\\Cos(31.7^{o})=\frac{0.81}{PR}$

The value of $Cos(31.7^{o})$ is 0.851 (**Use trigonometric calculator)

The value of PR is:

$cos(31.7^{o})=\frac{0.81}{PR} \\0.851=\frac{0.81}{PR} \\PR=\frac{0.81}{0.851} \\=0.9518\\\approx 0.95$

Thus, the length of side PR is 0.95 cm.

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