Question

Theta =30verify the following cos theta= underroot 1+cos2theta upon 2

Answer 1

Answer:Sin 2 theta is the sine of the angle which is double the value of theta. A formula to calculate sin 2 theta is: Sin 2 theta = 2 x (sin theta) x (cos theta) (x denotes multiplication) This can be used when you know the value of sine and cosine of theta and not 2 theta.

Step-by-step explanation:

The cosine double angle formula is cos(2theta)=cos2(theta) - sin2(theta). ... Cosine 2 theta is 1 minus 2 sine squared theta, cosine 2 theta equals 2 cosine squared minus 1.

Answer 2

Step-by-step explanation:

Φ= 30°

cosΦ=cos 30°=√3/2

Required to prove

cosΦ=√1+cos2Φ

cos 30°=√1+cos 2(30°)

√3/2=√1+cos 60°

√3/2=√1+1/2

√3/2=√3/2

L. H. S=R.H.S

Hence proved

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