18

 PAGE: 653 SET: Exercises PROBLEM: 18

Observe the figure:

The sides of the triangle are  and .

Consider, and .

Find .

(Pythagorean theorem)

(Substitute and )

(Evaluate powers and )

(Subtract from each side)

(Subtract: )

(Take the square root of each side)

(Cancel square and root)

(Substitute: )

Length can not be measure in negative values.

Therefore, the missing measure .

Find the trigonometric ratios for angle :

Formulas for angles of sine, cosine and tangent:

, and .

(Substitute   and )

(Substitute and )

(Substitute and )

, and .

, and .

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