Chapter 8 Class 10 Introduction to Trignometry
Example 6
Example 7 Important
Question 3 Important Deleted for CBSE Board 2025 Exams
Example 12 Important
Ex 8.1, 5 Important
Ex 8.1, 10 Important
Ex 8.1, 9 Important
Question 5 Important Deleted for CBSE Board 2025 Exams
Ex 8.1, 11 Important You are here
Question 6 Important Deleted for CBSE Board 2025 Exams
Question 7 Deleted for CBSE Board 2025 Exams
Ex 8.3, 1
Ex 8.3, 2 Important
Ex 8.3, 4 (i) Important
Chapter 8 Class 10 Introduction to Trignometry
Last updated at April 16, 2024 by Teachoo
Ex 8.1, 11 State whether the following are true or false. Justify your answer. (i) The value of tan A is always less than 1. tan A = (π πππ πππππ ππ‘π π΄ )/(π πππ ππππππππ‘ π΄) = π©πͺ/π¨π© Assuming BC >π¨π© Example: Let AB = 10 cm and BC = 15 cm Hence, tan A = π΅πΆ/π΄π΅ = 15/10 = 1.5 Therefore, tan A = 1.5 > 1 Hence tan A can be greater than 1 So, answer is false. Ex 8.1, 11 State whether the following are true or false. Justify your answer. (ii) sec A = 12/5 for some value of angle A. This statement is True As value of sec A > 1 Explanation sec A = π/ππ¨π¬β‘π¨ = 1/((ππππ ππππππππ‘ π‘π β π΄ )/π»π¦πππ‘πππ’π π) = π―πππππππππ/(πΊππ π ππ ππππππ ππ β π¨) As Hypotenuse will be the largest side, β΄ sec A > 1 As Hypotenuse will be the largest side, β΄ sec A > 1 Ex 8.1, 11 State whether the following are true or false. Justify your answer. (iii) cos A is the abbreviation used for the cosecant of angle A. This statement is False Because cos A means cosine of angle A cosec A means cosecant of angle A Ex 8.1, 11 State whether the following are true or false. Justify your answer. (iv) cot A is the product of cot and A. This statement is False Because cot A = 1/tanβ‘γ π΄γ =(πππ π ππ ππππππ π¨ )/(πππ π ππππππππ π¨) cot A is a single term and cot without A does not have any meaning Ex 8.1, 11 State whether the following are true or false. Justify your answer. (v) sin ΞΈ = 4/3 for some angle ΞΈ. sin ΞΈ = (πππ π ππππππππ π½)/π―πππππππππ Since hypotenuse is largest side, denominator will be always more than numerator . Hence, sin ΞΈ will always be always be less than 1 Thus, sin ΞΈ = 4/3 is false