CBSE Class 11 science: Sign of Trigonometric Functions Videos | Sign of Trigonometric functions

• sin(90+?)*.tan(270-?)*.cot(360-?)/cot(-?)*.tan(90+?)*.cos(180+?)=
  
• asec theta +btan theta=1 asec theta- btan theta=1 a^2(b^2+4)=
• plz answer them as fast as possible but with each step
  
• cos 840 find the value
• The following questions may kindly be answered.
  
• Prove that
• Prove that,
• Prove that,
• 
• 

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