Find the value of sin 75° + sin 15° = ?

• sin A + sin B = 2 sin [ (A + B) / 2 ] cos [ (A - B) / 2 ]
  =2 sin [ (75 +15) / 2 ] cos [ (75 - 15) / 2 ]
  =2 sin90cos60=2*1*(1/2)=1
• 9 years agoHelpfull: Yes(20) No(21)
• dentities will be used
  we can write
  sin 75=sin(45+30) and sin 15=sin(60-45)
  sin(a+b)=sina*cosb+cosa*sinb
  sin(a-b)=sina*cosb-cosa*sinb
  sin(45+30) + sin (60-45)
  sin45cos30+cos45sin30 + sin60cos45-cos60sin45
  putting values
  root3/root2 ............ i did mistake in calculation
• 9 years agoHelpfull: Yes(15) No(3)
• riya can u try this: sin(45+30)+sin(45-30)
  =sin45cos30+cos45sin30+sin45cos30-cos45sin30
  =2sin45cos30
  =sqrt(6)/2
• 9 years agoHelpfull: Yes(8) No(6)
• sin 75 + sin 15 = 2 sin (75+15)/2 cos (75-15)/2
  =2* sin 45 * cos 30
  =(3/2)^(1/2)
• 9 years agoHelpfull: Yes(8) No(2)
• i also get an answer root3/roo2 why it so
• 9 years agoHelpfull: Yes(3) No(0)
• identities will be used
  we can write
  sin 75=sin(45+30) and sin 15=sin(60-45)
  sin(a+b)=sina*cosb+cosa*sinb
  sin(a-b)=sina*cosb-cosa*sinb
  sin(45+30) + sin (60-45)
  sin45cos30+cos45sin30 + sin60cos45-cos60sin45
  putting values
  3/2+3/2=6/2=3
• 9 years agoHelpfull: Yes(2) No(6)
• is it 1/root2 ???
• 9 years agoHelpfull: Yes(1) No(3)
• Ans is sqrt(6)/2
• 9 years agoHelpfull: Yes(1) No(2)
• bhai shahab calculator allowed hai TCS me.....
• 9 years agoHelpfull: Yes(1) No(1)
• sina+sinb=sin(a+b/2)+cos(a-b/2)
  =(3/2)^(1/2)
• 9 years agoHelpfull: Yes(0) No(2)
• Ans::1 because sin A+sin B=sin(A+B)
• 9 years agoHelpfull: Yes(0) No(3)
• =sin(45+30)+sin(45-30)
  (=>sin(a+b)=sin a*cos b+cos a*sin b and sin(a-b)=sin a*cos b-cos a*sin b)
  =sin45*cos 30+cos45*sin 30 +sin45*cos30-cos45*sin30
  =2*sin45*cos30
  =2*(1/sqrt 2)*(1/2)
  ans. =1/sqrt 2
• 9 years agoHelpfull: Yes(0) No(0)
• sin15=sin(45−30)=sin45.cos30−sin30.cos45
  sin75=sin(30+45)=sin30.cos45+sin45.cos30
  
  sin15=sin(45−30)=sin45.cos30−sin30.cos45=2–√2.3–√2−12.2–√2=6–√−2–√4
  
  sin75=sin(30+45)=sin30.cos45+sin45.cos30=12.2–√2+2–√2.3–√2=2–√+6–√4
  
  sin15+sin75=6–√−2–√4+2–√+6–√4=26–√4=6–√2 :D
• 5 years agoHelpfull: Yes(0) No(0)
• sin 75 + sin 15
  = 2sin [(75+15)/2] * cos [(75-15)/2]
  = 2sin[90/2]*cos[60/2]
  = 2sin45*cos30
  = 2*1/(2^1/2)*(3^1/2)/2
  = (3/2)^1/2
  root (3/2)
• 4 years agoHelpfull: Yes(0) No(0)