Here you get the CBSE Class 10 Mathematics chapter 8, Introduction to Trigonometry and its Applications: NCERT Exemplar Problems and Solutions (Part-IVA). This part includes solutions of Question Number 1 to 6 from Exercise 8.4 of NCERT Exemplar Problems for Class 10 Mathematics Chapter: Introduction to Trigonometry and its Applications. This exercise comprises only the Long Answer Type Questions framed from various important topics in the chapter. Each question is provided with a detailed solution.

**CBSE Class 10 Mathematics Syllabus 2017-2018**

NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. All these questions are very important to prepare for CBSE Class 10 Mathematics Board Examination 2017-2018 as well as other competitive exams.

**Find below the NCERT Exemplar problems and their solutions for Class 10 Mathematics Chapter, Introduction to Trigonometry and its Applications:**

**Exercise 8.4**

**Long Answer Type Questions (Q. No. 1-6)**

**Question. 3 **The angle of elevation of the top of a tower from certain point is 30°. If the observer moves 20m towards the tower, the angle of elevation of the top increases by 15°. Find the height of the tower.

**Solution**.

Let *AC* be the *h * metre high tower and *B* be the initial point from where angle of elevation of the top of tower is observed.

Let after moving 20m towards tower, observer stands on point *D* with angle of elevation being 30^{o} +15^{o} = 45^{o} and *x* metres away from the foot of tower.

**Question. 5 **If sin*θ* + 2cos*θ* = 1, then prove that 2 sin*θ *- cos*θ* = 2.

**Solution**.

**Question. 6 **The angle of elevation of the top of a tower from two points distant s and *t *from its foot are

**Solution**.

Let *AC* be the *h * metre high tower* *and *θ* and (90° – *θ*) be the angles of elevation for distances *s* and *t* respectively.

[As the two angles of elevation are given to be the complementary angles]

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