398. Examples in Multiplication. Determine the following products on the slide-rule and check by logarithmic computation.

Diagram the setting for not less than six examples, in three of which the slide projects to the right, and in the other three to the left. In all examples show the direction of the slide and the equation for pointing off.

* cos denotes the cosine, which is the complement's sine.

§ 7. DIVISION

399. How to Divide.

Division is performed on the

slide-rule by setting runner and slide so that the logarithm of the divisor may be subtracted from the logarithm of the dividend, as follows:

(1) Set the runner to the dividend on D.

(2) Set the divisor on C under the runner.

(3) Set the runner to the C index.

(4) Read the quotient on D under the runner.

Briefly: Set the divisor on C over the dividend on D and read the quotient on D under the C index.

1 in the diagram denotes the C index which may be the right or the left depending on which one is " on the rule."

400. Rule for Pointing Off a Quotient. The number of integral figures in a quotient read with the C and D scales, equals the following:

(1) The number of integral figures in the dividend minus the number of integral figures in the divisor when the slide projects to the left.

(2) One more than the difference between the number of integral figures in dividend and divisor when the slide projects to the right.

401. Examples in Division. With the slide-rule determine the following quotients. Diagram not less than six settings, three with the slide to the right and three with the slide to the left, with equations for pointing off. Check the results by logarithms.

CHAPTER XVI

THE SOLUTION OF A TRIANGLE

SECTION 1. FUNCTIONS OF ANGLES. SECTION 2. SOLUTION OF A RIGHT TRIANGLE. SECTION 3. SOLUTION OF AN OBLIQUE TRIANGLE.

§ 1. FUNCTIONS OF ANGLES

402. An Angle. The amount of opening or divergence of two straight lines which have one point in common is called an angle. The divergence is expressed in degrees, a degree being one-ninetieth of a right angle.

Angles are classified as follows:

Obtuse, greater than 90° and less than 180°;

403. A Triangle. When three straight lines inclose space, a triangle is formed. A triangle has six parts:

3 angles, and 3 sides.

The different kinds of triangles are shown below:

AADA

Acute

Obtuse

Right

Isosceles

FIG. 188.