CBSE Class 10 Mathematics Trigonometry Assignment Set A

I. Children were playing a game by making some right angled triangles on the plane sheet of paper. They assumed angles and their corresponding sides.
They wanted to find all trigonometric ratio so they took a right angled triangle with two of its sides AC = 13 cm, BC = 12 cm and –ABC = 90º. They are unable to find trigonometric ratio. So help them to do so.

Question. Using the above data, the value of sin A is
(a) 12/13
(b) 13/12
(c) 5/13
(d) 13/5
Answer : A

Question. Using the above data, the value of sin C is
(a) 12/13
(b) 13/12
(c) 5/13
(d) 13/5
Answer : C

Question. Using the above data, the value of tan C is
(a) 12/5
(b) 12/13
(c) 13/12
(d) 5/12
Answer : D

Question. Using the above data, the value of cos A is
(a) 12/5
(b) 13/5
(c) 5/13
(d) 12/13
Answer : C

Question. Using the above data, the value of tanA + sinA / tanA - sinA is
(a) 9/4
(b) 4/9
(c) 12/9
(d) 9/13
Answer : A
 

II. Some students of class-X of a school were asked to show trigonometric ratio of 60° on the top of the table using some sticks. The students were excited to do this case.
So, they took 4 sticks. Three of them were equal and the 4th stick was smaller than the three. They put the sticks as shown in the given figure ΔABC and height AD.

AB = BC = CA = 2a (say)
AB² = AD² + BD²
(2a)² = AD² + (1/2 BC)²
4a² = AD² + (1/2 2a)²
4a² = AD² + a²
∴ AD² = 3a²
∴ AD = √3 a
On the basis of above information, students answered their teacher’s questions, which are as follows:

Question. What is the value of sin 60°?
(a) √3/2
(b) 2/√3
(c) 1/2
(d) 1/√3
Answer : A

Question. The value of cos 60° is
(a) 1/√3
(b) 3
(c) 1/2
(d) 1/√2
Answer : C

Question. What is the value tan 60°?
(a) 1/√3
(b) 3
(c) √3/2
(d) 1/√2
Answer : B

Question. The value of 1+sinB/cosB when ∠B = 60° is
(a) 3√3
(b) 2 – √3
(c) 2√3
(d) 2 + √3
Answer : D

Question. The value of 1 + tan² B/1 + cot² B when ∠B = 60° is
(a) 3
(b) 4
(c) 3√3
(d) 4√3
Answer : A