At a point on level ground

MATHEMATICS · Multi-part · CBSE · Mathematics · Inverse Trigonometric Functions · Inverse Trigonometric Functions

Problem

At a point on level ground, a tower subtends an angle of elevation α\alpha whose tangent is 34\tfrac34. (i) Without finding α\alpha, express sin⁡α\sin\alpha and cos⁡α\cos\alpha as rational numbers. (ii) Using your answers from part (i), calculate sin⁡(arctan⁡34)+cos⁡(arctan⁡34)\sin\bigl(\arctan\tfrac34\bigr)+\cos\bigl(\arctan\tfrac34\bigr). (iii) Evaluate cos⁡(arcsin⁡35)\cos\bigl(\arcsin\tfrac35\bigr), giving the result in simplest radical form.

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