Question

f Case study question... : Case Study 2 Radha was working in Maths Lab with a sharp pointed ball pen. She put the pointed tip of pen AC in a tiny hole in the drawing board to make it stand upright position shown in fig. sun light coming form window caused the shadow of pen to appear on plane drawing board (BC in fig.) coincidently the introduction to Trigonometry chapter was being done in class. As a practical demonstration to the concept teacher Mr. Shamlal asked these questions after students have measured that length of shadow is 13 times the length of pen. A Pen R Shadow​

Answer 1

Answer:

1)c) tan theta

2)b) 30

3)a)40 cm (question has a typing error it is cm)

4)c)

Answer 2

The answers are:

Q.1: c) tan$\theta$

Q.2: b) 30 degrees

Q.3: b) 35 cm

Q.4: c)

Step-by-step explanation:

• In the given question, the length of the pen is known and the length of the shadow is also determined. Since the angle ACB is a right angle, thus, making sides AC and BC as the sides (perpendicular and base) of the triangle, hence, we can use the identity tan$\theta$, since it relates perpendicular with the base.

Hence, the answer for Q.1 is c) tan$\theta$

• Given, length of pen = AC, length of shadow =BC = $\sqrt{3} \times$AC

$tan\theta = \frac{AC}{BC} =\frac{1}{\sqrt{3} }$

The value of tan30 is equal to $\frac{1}{\sqrt{3}}$. So, angle ABC is 30 degrees.

Hence, the answer for Q.2 is b) 30 degrees

• Given, the length of the pen = 20 cm,

the length of the shadow $= \sqrt{3} \times 20 = 1.732 \times 20 = 34.64 = 35cm$

Hence, the answer for Q.3 is b) 35 cm

• Trigonometric equations are framed for a particular situation and may change depending upon the situation of the question, but, trigonometric identities are applicable to all situations.

Hence, the answer for Q.4 is c).