question_answer

 

Directions: Q. 6 to 10

Kavita a student of class 10th, has to made a project on 'Introduction to Trigonometry'. She decides to make a Dog house which is triangular in shape.

She uses cardboard to make the Dog house as shown in the figure.

Considering the front side of Dog house as right angled triangle PQR, right angled at R, answer the following questions.

If \[\angle PQR=\theta \], then \[\cos \theta \]is equal to

A) \[\frac{4}{5}\]

B) \[\frac{5}{12}\]

C) \[\frac{3}{5}\]

D) \[\frac{13}{12}\]

Correct Answer: A

Solution :

Given, \[\angle PQR=\theta\] and             \[\angle R=90{}^\circ\]

\[\cos \theta =\frac{QR}{PQ}=\frac{12}{15}=\frac{4}{5}\]