NCERT Solutions of Class 10 Maths Chapter 8: Introduction to Trigonometry

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NCERT Solutions of Class 10 Maths Chapter 8 Introduction to Trigonometry are given in the article. Trigonometry studies relationships between side lengths and angles of triangles. Chapter 8 Introduction to Trigonometry solutions cover key concepts such including Trigonometric ratios of an acute angle of a right-angled triangle & their proofs. Values of the trigonometric ratios of 300, 400, and 600 and relationships between Ratios.

Class 10 Maths Chapter 8 Introduction to Trigonometry is a part of Unit 5 Trigonometry. This unit holds a weightage of 12 Marks in Class 10 Maths Examination 2022-23. NCERT Solutions of Class 10 Maths Chapter 8 are based on the following topics:

Download: NCERT Solutions for Class 12 Mathametics Chapter 8 pdf


NCERT Solutions of Class 10 Maths Chapter 8 Introduction to Trigonometry

NCERT Solutions of Class 10 Maths Chapter 8 Introduction to Trigonometry are provided below: 

Also check: Introduction to Trigonometry


Important Topics: NCERT Solutions of 10 Maths Chapter 8 Introduction to Trigonometry

Important Topics of NCERT Solutions of 10 Maths Chapter 8 Introduction to Trigonometry are elaborated below:

Trigonometric Identities

There are 6 kinds of Trigonometric Idenities:

  • Sine 
  • Cosine 
  • Tangent 
  • Secant 
  • Cosecant 
  • Cotangent

Example Prove the following identity using the trigonometric identities:

[(sin 3θ + cos 3θ)/(sin θ + cos θ)] + sin θ cos θ = 1

Solution: Let’s the following identity:

a3+b3 = (a+b)(a2-ab+b2)

Using Pythagoras Theorem, 

L.H.S. = [(sin 3θ + cos 3θ)(sin θ + cos θ)] + sin θ cos θ

= [(sin θ + cos θ)(sin2θ - sin θ cos θ + cos2θ)(sin θ + cos θ) + sin θ cos θ

= (sin2θ - sin θ cos θ + cos2θ) + sin θ cos θ

= sin2θ + cos2θ = 1 = R.H.S.

Trigonometry Table

Trigonometry Table is a collection of values of trigonometric ratios for various standard angles including 0°, 30°, 45°, 60°, 90°, sometimes with other angles like 180°, 270°, and 360° included, in a tabular format.

Example: Calculate the exact value of sin15º using the trigonometric value for standard angles from a trigonometry table.

Solution: Using the trigonometric table, we know that sin45º = 1/√2, cos30º = (√3/2), cos45º = 1/√2, and sin30º = 1/2

sin15º = sin(45º - 30º) = sin45ºcos30º - cos45ºsin30º = (√2/2) • (√3/2) - (√2/2) • (1/2) = (√6 - √2)/4 = (√3 - 1)/2√2

Therefore, tThe value of sin15º = (√3 - 1)/2√2

Trigonometry Ratios

Trigonometric ratios are the “ratios of length of sides of a triangle”.

Trigonometric ratios relate the ratio of sides of a right triangle to the respective angle. Basic trigonometric ratios are sin, cos, and tan. Other important trigonometric ratios, cosec, sec, and cot, can be derived using the sin, cos, and tan respectively.

Sum, Difference, Product Trigonometric Ratios Identities

Sum, Difference, Product Trigonometric Ratios include the following formulas:

  • sin (A + B) = sin A cos B + cos A sin B
  • sin (A - B) = sin A cos B - cos A sin B
  • cos (A + B) = cos A cos B - sin A sin B
  • cos (A - B) = cos A cos B + sin A sin B
  • tan (A + B) = (tan A + tan B)/ (1 - tan A tan B)
  • tan (A - B) = (tan A - tan B)/ (1 + tan A tan B)
  • cot (A + B) = (cot A cot B - 1)/(cot B - cot A)
  • cot (A - B) = (cot A cot B + 1)/(cot B - cot A)
  • 2 sin A⋅cos B = sin(A + B) + sin(A - B)
  • 2 cos A⋅cos B = cos(A + B) + cos(A - B)
  • 2 sin A⋅sin B = cos(A - B) - cos(A + B)

NCERT Solutions For Class 10 Maths Chapter 8 Exercises

The detailed solutions for all the NCERT Solutions for Introduction to Trigonometry under different exercises are as follows:

Also check:

Also check:

CBSE X Related Questions

  • 1.

    The following data shows the number of family members living in different bungalows of a locality:
     

    Number of Members0−22−44−66−88−10Total
    Number of Bungalows10p60q5120


    If the median number of members is found to be 5, find the values of p and q.


      • 2.
        A peacock sitting on the top of a tree of height 10 m observes a snake moving on the ground. If the snake is $10\sqrt{3}$ m away from the base of the tree, then angle of depression of the snake from the eye of the peacock is

          • $60^\circ$
             

          • $45^\circ$
          • $30^\circ$
          • $90^\circ$

        • 3.

          Two identical cones are joined as shown in the figure. If radius of base is 4 cm and slant height of the cone is 6 cm, then height of the solid is

            • 8 cm
            • \(4\sqrt{5}\) cm
            • \(2\sqrt{5}\) cm
            • 12 cm

          • 4.

            Find the mean and mode of the following data:

            Class15--2020--2525--3030--3535--4040--45
            Frequency1210151175


              • 5.
                OAB is sector of a circle with centre O and radius 7 cm. If length of arc \( \widehat{AB} = \frac{22}{3} \) cm, then \( \angle AOB \) is equal to

                  • \( \left(\frac{120}{7}\right)^\circ \)
                  • \( 45^\circ \)
                  • \( 60^\circ \)
                  • \( 30^\circ \)

                • 6.
                  The number of red balls in a bag is three more than the number of black balls. If the probability of drawing a red ball at random from the given bag is $\dfrac{12}{23}$, find the total number of balls in the given bag.

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