Q4 of 46 Page 284

Is it right to say cos(60° + 30°) = cos 60° cos 30° - sin 60° sin 30°.

Let us solve Left-Hand-Side:

cos (60° + 30°) = cos 90°


⇒ cos (60° + 30°) = 0 [∵, cos 90° = 0]


Now, solve for Right-Hand-Side:



⇒


⇒ cos 60° cos 30° - sin 60° sin 30° = 0


More from this chapter

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2

Choose the right option and justify your choice -

C)


A. cos 60°


B. sin 60°


C. tan 60°


D. sin 30°

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Evaluate sin 60° cos 30° + sin 30°cos 60°. What is the value of sin(60° + 30°). What can you conclude?

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In right angle triangle ΔPQR, right angle is at Q and PQ = 6cms ∠RPQ = 60°. Determine the lengths of QR and PR.

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In right angle is at Y, YZ = x and XZ = 2x then determine ∠YXZ and ∠YZX.