This unit will cover the relationships among the sides and angles of the right triangle, that is a triangle with one 90° angle.
After completing this chapter, the student will be able to use a calculator and EXCEL to:
- Calculate all sides and angles of a right triangle when given one acute angle and one side.
- Calculate all sides and angles of a right triangle when given two sides.
The trigonometric functions in the calculator perform two functions. Given the angle, the calculator will return the ratio of the sine, cosine and tangent. Given the ratio of the sine, cosine, or tangent, the calculator will return the angle.
The calculator recognizes three measurement scales for angles: degrees, radians, and grads. Which of these modes is in effect is shown on the calculator screen.
To get the sine of 30° be sure the calculator is in the Degree mode and press the keys:
3 0 SIN = :The calculator will show 0.5.
To get the angle when the sine is 0.5 use the keys: . 5 INV SIN =
The calculator will show 30.
Some calculators have separate keys for the process of finding the arcsine, arccosine and arctangent. These keys have a "-1" superscript. for those calculators press the keys:
. 5 SIN-1 =: The calculator will show 30.
The trigonometric functions in EXCEL are available under the Insert Menu . Given the angle, EXCEL will return the ratio of the sine, cosine and tangent. Given the ratio of the sine, cosine, or tangent, EXCEL will return the angle.
EXCEL, however, recognizes angles only in radians. There is help. The Function RADIANS converts degrees to radians. The Function DEGREES converts radians to degrees.
