Find the sign of expression sin100°+cos100°

1.	Find the sign of expression sin100°+cos100°
Answer» Sin 100° + cos 100°= sin 100° + cos ( 90°+10°) =sin 100°+(-sin10°) (By the formula cos (π/2+x)= -sin x) =2 cos((100+10)/2)* Sin((100-10) /2) =2cos 55°sin45°=2cos 55° 1/√2=√2√2 cos 55°1/√2=√2cos 55° Or = (1.4)*(0.57) =0.8<br>sin 100° + cos 100°= sin100° + cos(90°+10°)[cos 10° becomes sin 10°]= sin100° + sin 10°by the formula,sin C + sin D = 2cos\xa0sin= 2cos\xa0sin= 2cos\xa0\xa0sin\xa0= 2cos55° + sin45°= 2cos55° + 1/√2=√2.√2 cos55° .1/√2= √2cos55°

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