Introduction to Trigonometry

What you'll learn

The three ratios, the SOH-CAH-TOA memory trick, the standard-angle table, and the key identity.

This chapter has

Introduction to Trigonometry — solved practice questions

6 Class 10 Mathematics questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1easy

   In a right-angled triangle, sin θ is defined as:

   • Aopposite / hypotenuse
   • Badjacent / hypotenuse
   • Copposite / adjacent
   • Dhypotenuse / opposite
   Show answer & solution

   Correct answer: (A) opposite / hypotenuse

   sin θ = opposite side / hypotenuse.

2. Q2easy

   In a right-angled triangle, cos θ is defined as:

   • Aopposite / hypotenuse
   • Badjacent / hypotenuse
   • Copposite / adjacent
   • Dadjacent / opposite
   Show answer & solution

   Correct answer: (B) adjacent / hypotenuse

   cos θ = adjacent side / hypotenuse.

3. Q3medium

   The value of sin 30° is:

   • A1/2
   • B√3/2
   • C1
   • D0
   Show answer & solution

   Correct answer: (A) 1/2

   sin 30° = 1/2 (a standard value to memorise).

4. Q4easy

   The value of cos 0° is:

   • A0
   • B1
   • C1/2
   • D√3/2
   Show answer & solution

   Correct answer: (B) 1

   cos 0° = 1.

5. Q5medium

   The value of tan 45° is:

   • A0
   • B1
   • C√3
   • D1/√3
   Show answer & solution

   Correct answer: (B) 1

   tan 45° = 1 (since sin 45° = cos 45°).

6. Q6medium

   The identity sin²θ + cos²θ equals:

   • A0
   • B1
   • C2
   • Dtan²θ
   Show answer & solution

   Correct answer: (B) 1

   sin²θ + cos²θ = 1 — the fundamental trigonometric identity.

Want the full set? Practise all 6 Introduction to Trigonometry questions →