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(#M40040543) TCS Numerical Ability question trignometry Keep an EYE

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

Asked In TCS ANUP KUMAR GUPTA (10 years ago)

Solved swapnil saxena Read Solution (14)

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Read Solution (14) :

swapnil saxena  (10 years ago) Best Solution

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

Is this solution Helpfull? Yes (20) | No (21)  

riya  (10 years ago)

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

Is this solution Helpfull? Yes (15) | No (3)  

ASHUTOSH KUMAR  (10 years ago)

riya can u try this: sin(45+30)+sin(45-30)
=sin45cos30+cos45sin30+sin45cos30-cos45sin30
=2sin45cos30
=sqrt(6)/2

Is this solution Helpfull? Yes (8) | No (6)  

Shamik Mukherjee  (10 years ago)

sin 75 + sin 15 = 2 sin (75+15)/2 cos (75-15)/2
=2* sin 45 * cos 30
=(3/2)^(1/2)

Is this solution Helpfull? Yes (8) | No (2)  

apra  (10 years ago)

i also get an answer root3/roo2 why it so

Is this solution Helpfull? Yes (3) | No   

riya  (10 years ago)

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

Is this solution Helpfull? Yes (2) | No (6)  

Srinanda Nandy  (10 years ago)

is it 1/root2 ???

Is this solution Helpfull? Yes (1) | No (3)  

samiksha  (10 years ago)

Ans is sqrt(6)/2

Is this solution Helpfull? Yes (1) | No (2)  

shaurya neel  (10 years ago)

bhai shahab calculator allowed hai TCS me.....

Is this solution Helpfull? Yes (1) | No (1)  

RABI KR. SHAW  (10 years ago)

sina+sinb=sin(a+b/2)+cos(a-b/2)
=(3/2)^(1/2)

Is this solution Helpfull? Yes | No (2)  

Narala Sudheer Yadav  (10 years ago)

Ans::1 because sin A+sin B=sin(A+B)

Is this solution Helpfull? Yes | No (3)  

MILY SAXENA  (10 years ago)

=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

Is this solution Helpfull? Yes | No   

Shubhi Vyas  (6 years ago)

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

Is this solution Helpfull? Yes | No   

Ashutosh Mishra  (5 years ago)

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)

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