## Free PDF download of RD Sharma Solutions for Class 10 Maths Chapter 12 - Some Applications of Trigonometry

## FAQs on RD Sharma Class 10 Math Some Applications of Trigonometry Solutions - Free PDF Download

**1. How important is Trigonometry for the class 10 Maths Board Exam?**

Because of the complex and tricky formula, students tend to skip this chapter despite its importance while pursuing Engineering, Astronomy and Physics. This chapter cannot be cleared without practicing the formula regularly since there are so many to remember at once. When students begin their preparation, they should first make a chart of important formulas and keep it visible in their study for reference and to help learn it. At least four to five questions from this chapter are asked every year in the board exams hence Trigonometry has to be practiced regularly.

**2. How do we calculate the sum and the differences of two angles?**

As stated above, Trigonometry has three important trigonometric ratios which are the most important parts of this chapter: sin, cos and tan. All the trigonometric identities are formed based on these three ratios. So to derive the sum and difference of two angles, let us assume that there are two angles, A and B. The following will be the equations formed:

Sin (A+B)= sinAcosB+ cosAsinB

Sin (A-B)= sinAcosB- cosAsinB

Cos (A+B)= cosAcosB-sinAsinB

Cos (A-B)= cosAcosB+sinAsinB

Tan (A+B)=(tan A+tan B)/(1-tanAtanB)

Tan (A-B)=(tan A-tan B)/(1+tanAtanB)

**3. What are double and triple angle identities in Trigonometry?**

A double angle formula is a trigonometric identity which expresses a trigonometric function of 2𝛳 and triple angle formula expresses trigonometric function of 3𝛳. These are special cases of compound angle formulas. The formula for both the double angle and triple angle identities are given below as:

For double angle:

sin2A = 2sinA cosA = [ 2 tan A + (1+tan2A)]

cos2A = cos2A–sin2A = 1–2sin2A = 2cos2A–1= [(1-tan2A)/(1+tan2A)]

tan 2A = (2 tan A)/(1-tan2A)

For triple angle:

sin3A = 3sinA-4sin3A

cos3A = 4cos3A-3cosA

tan3A = [3tanA-tan3A]/[1-3tan2A]

**4. How are the applications of Trigonometry as suggested in R. D. Sharma?**

Trigonometry has several applications mainly in the field of engineering, aviation, criminology, astronomy, architecture, oceanography and game development. They are even used in music where the wave patterns in the form of sine and cosine can be used to develop music on the computer. In this chapter, the major discussion revolves around measuring the height of a building or a mountain. The trigonometric functions used here are calculated by the distance of the building from a viewpoint and the elevation angle.

**5. Are the questions on application of Trigonometry difficult?**

If a student has great grip on his knowledge of the trigonometric identities, formulas and functions, this chapter will seem like a piece of cake. This is because, in this chapter, the basic trigonometric functions have been used to calculate height, length and distance of objects. In case of confusion, go through the examples for help. Try to solve those, then move ahead with the easy questions and as the foundation becomes stronger, climb the ladder and solve the complex ones. Students must practice strengthening their understanding of Trigonometry. Students download free study material from Vedantu site and app