4.4. Right Triangle Trigonometry http://www.ck12.org
Solution:This problem can be solved using sin, cos or tan because the opposite, adjacent and hypotenuse lengths
are all given.
The argument of a sin function is always an angle. The arcsin or sin−^1 θfunction on the calculator on the other hand
has an argument that is a side ratio. It is useful for finding angles that have that side ratio.
sinA= 135
A=sin−^1( 5
13
)
≈ 0. 39 radian≈ 22. 6 ◦Example C
Given a right triangle witha= 12 in,m^6 B= 20 ◦,andm^6 C= 90 ◦, find the length of the hypotenuse.
Solution:
cos 20◦=^12 c
c=cos 20^12 ◦≈ 12. 77 inConcept Problem Revisited
Instead walk 10 feet away and notice that the flag pole makes a 65◦angle with your feet.
If you walk 10 feet from the base of a flagpole and assume that the flagpole makes a 90◦angle with the ground.