EXAMPLE

Given an acute angle and adjacent side in figure 20, find angle B and sides

"a" and "c."

SOLUTION

Here, "a" is the side opposite and "c" is the hypotenuse. Angle B = 90,, - A

= 61,, 39'.

According to rule (6)(see page 53), side opposite = side

adjacent ƒ tangent, or rule (7)(see page 53), side opposite = side adjacent

ƒ cotangent. Substituting .300 meters for side adjacent and .5396 for tan,

side opposite = .300 x .5396 = .1619 meter. Or, substituting .300 for side

adjacent and 1.8533 for cotangent, side opposite = .300 ƒ 1.8533 = .1619.

According to rule (12)(see page 54), hypotenuse side adjacent ƒ cosine.

Substituting .300 for side adjacent and .8801 for cosine, hypotenuse = .300

ƒ .8801 = .34087.

FIGURE 20.

FIND ANGLE B AND SIDES "A" AND "C."