Right Triangle Trigonometry Exercise 2

Reference Triangle

Right Triangle
Right Triangle

Instructions for Exercise 2

Here is the second of three examples. Use the triangle to the right for reference. The solution is at the bottom of the post. A trig table and the trig wheels are also included.

The length of side A is 100, and the length of side C is 42. Find the length of the hypotenuse and angles 1 and 2.

Solution for Exercise 2

This solution demonstrates one of a number of possible ways to come to the values in bold; the important thing is to arrive at the same values shown for each unknown.

The length of side A is 100, and the length of side C is 42. Find the length of the hypotenuse and angles 1 and 2.

Angle 1 can be found by dividing opposite side 42 by adjacent side 100. The tangent of angle 1 is 0.42. The table shows that the angle associated with a tangent of .42 is (approx.) 23°.

Angle 2 is found by subtracting 23° from 90°. Angle 2 is 67°.

The hypotenuse (side B) is found by taking the side adjacent to angle 1 (side A), 100, and dividing it by the cosine of angle 1 (angle 1 is 23°, therefore the cosine is 0.9205). Side B is equal to 100/.9205 or 108.64.

Trig Wheels

Trig Wheels
Trig Wheels

Click on the trig table to see it full size

Trig Table
Trig Table

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2 comments

nms profile image

nms 7 years ago from Cochin

reminded me my math class, i want my school days back!:(


puppascott profile image

puppascott 7 years ago from Michigan (As far as you know...) Author

Don't we all.

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