Class 10 Maths Chapter 8 Solutions in Hindi and English.
Important NCERT Questions
Introduction Trigonometry
NCERT Books for Session 2022-2023
CBSE Board and UP Board Others state Board
EXERCISE 8.3
Page No:187
Questions No:2
(i) tan 48° tan 23° tan 42° tan 67° = 1
(ii) cos 38° cos 52° – sin 38° sin 52° = 0
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(i) tan 48° tan 23° tan 42° tan 67° = 1
LHS = tan 48° tan 23° tan 42° tan 67°
= tan 48° tan 23° cot(90°-42°) cot(90°-67°) [∵ cot(90°-θ) = tanθ]
= tan 48° tan 23° cot 48° cot 23°
= tan 48° tan 23° × 1/tan 48° × 1/tan 23°
= 1 = RHS
(ii) cos 38° cos 52° – sin 38° sin 52° = 0
LHS = cos 38° cos 52° – sin 38° sin 52°
= cos 38° cos 52° – cos (90°-38°) cos (90°-52) [∵ cos (90°-0°) = sinθ]
= cos 38° cos 52° – cos52° – cos 38°
= 0 = RHS
see this video explanation of the above question🧐