1.

Fill in the blanks. i. sin 20° = cos ....° ii. tan 30° x tan.....° = 1iii. cos 40° = sin .......°

Answer»

i. sin 20° = cos (90° – 20°) …..[∵ sin θ = cos (90 – θ)] 

= cos 70° 

ii. tan θ x tan (90 – θ) = 1 

Substituting θ = 30°,

 tan 30° x tan (90 – 30)° = 1 

∴ tan 30° x tan 60° = 1 

iii. cos 40° = sin (90° – 40°) …[∵ COS θ = sin (90 – θ)] 

= sin 50°



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