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Without using trigonometric tables, prove that: (i) cos 81∘−sin 9∘=0 (ii) tan 71∘−cot 19∘=0 (iii) cosec 80∘−sec 10∘=0 (iv) cosec272∘−tan218∘=1 (v) cos275∘+cos215∘=1 (vi) tan266∘−cot224∘=0 (vii) sin248∘+sin∘42∘=1 (viii) cos257∘=sin233∘=0 (ix) (sin 65∘+cos25∘)(sin 65∘−cos 25∘)=0 |
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Answer» Without using trigonometric tables, prove that: (i) cos 81∘−sin 9∘=0 (ii) tan 71∘−cot 19∘=0 (iii) cosec 80∘−sec 10∘=0 (iv) cosec272∘−tan218∘=1 (v) cos275∘+cos215∘=1 (vi) tan266∘−cot224∘=0 (vii) sin248∘+sin∘42∘=1 (viii) cos257∘=sin233∘=0 (ix) (sin 65∘+cos25∘)(sin 65∘−cos 25∘)=0 |
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