Datrys 4(sin(150)cos(135)+cos(240)sin(135))

$$4( \sin ( 150 ) \cos ( 135 ) + \cos ( 240 ) \sin ( 135 ) )$$

Enrhifo

$$-2\sqrt{2}\approx -2.828427125$$

Camau Ateb

Defnyddio \sin(x)\cos(y)=\frac{1}{2}\left(\sin(x-y)+\sin(x+y)\right) i gael y canlyniad.

$$4\left(\frac{1}{2}\left(\sin(150-135)+\sin(150+135)\right)+\cos(240)\sin(135)\right)$$

Tynnu 135 o 150. Adio 135 at 150.

$$4\left(\frac{1}{2}\left(\sin(15)+\sin(285)\right)+\cos(240)\sin(135)\right)$$

Gwnewch y gwaith cyfrifo.

$$4\left(-\frac{1}{4}\sqrt{2}+\cos(240)\sin(135)\right)$$

Defnyddio \sin(x)\cos(y)=\frac{1}{2}\left(\sin(x-y)+\sin(x+y)\right) i gael y canlyniad.

$$4\left(-\frac{1}{4}\sqrt{2}+\frac{1}{2}\left(\sin(135-240)+\sin(135+240)\right)\right)$$

Tynnu 240 o 135. Adio 240 at 135.

$$4\left(-\frac{1}{4}\sqrt{2}+\frac{1}{2}\left(\sin(-105)+\sin(375)\right)\right)$$

Gwnewch y gwaith cyfrifo.

$$4\left(-\frac{1}{4}\sqrt{2}-\frac{1}{4}\sqrt{2}\right)$$

Cyfuno -\frac{1}{4}\sqrt{2} a -\frac{1}{4}\sqrt{2} i gael -\frac{1}{2}\sqrt{2}.

$$4\left(-\frac{1}{2}\right)\sqrt{2}$$

Lluosi 4 a -\frac{1}{2} i gael -2.

$$-2\sqrt{2}$$