# Math Help - Trigonometry

1. ## Trigonometry

Hi. I have the triangle PQR pq=17cm , qr=15cm and pr=8cm

I need to write down the values of sinQ,cos Q and tan Q. I know the soh,cah,toa rules but not sure how to apply them. Thank you.

Also i need to sketch curves such as y=sin x for 0degrees <and equal to x <and equal to 360degrees. then solve the equation sin x=0.5 for 0degree <and equa to x <and equal to 360 degree then illustrate these on the sketch.

I have only just started this subject and this is a beginner exercise before we begin the main lessons into it, so i would be grateful for any guidence you can give.

Thank you

2. Hello, Chez!

Ha! . . . I mislabelled my diagram!

I have the triangle PQR: . $PQ=17\text{ cm, }\:QR=15\text{ cm, and }\:PR=8\text{ cm}$

Find: . $\sin Q,\;\cos Q,\;\tan Q$
Code:
    P *
|  *
|     *   17
8 |        *
|           *
|              *
R * - - - - - - - - * Q
15

Note that: . $8^2 + 15^2 \:=\:17^2$
. . The sides satisfy the Pythgorean Theorem.

Hence, $\Delta PQR$ is a right triangle.

Therefore:

. . $\begin{array}{ccccc}\sin Q & = &\dfrac{8}{17} \\ \\[-2mm] \cos Q & = & \dfrac{15}{17} \\ \\[-2mm] \tan Q & = & \dfrac{8}{15} \end{array}\quad \hdots$ . corrected

3. I did the pythagorous thery at the beginning
to find the sin etc the questions says the keep the answer as a fraction, so it cant be a whole number..