How to tell when to use sin, cos or tan

Step-by-step explanation:

Keep in mind that these three trig functions can be interpreted as being the ratios of the side lengths of a triangle:

            opposite side

sin x =

              hypotenuse

            adjacent side

cos x =

              hypotenuse

            opposite side

tan x =

             adjacent side

In the case where you have a right triangle and know the lengths of two of its three sides, that knowledge dictates which of the above trig functions to use in "solving the triangle."

If, for example, the "opposite side" of a triangle is 3 and the "hypotenuse" is 5, we'd choose to use the sine function to find the angle opposite the "opposite side:"

            opposite side       3 units

sin x = =

              hypotenuse         5 units

Find x by using the inverse sine function:

Angle x = arcsin 3/5 = 0.644 radians or 36.9 degrees.

proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles.(more about triangle types) therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.

step-by-step explanation:

an isosceles triangle has two congruent sides and two congruent angles. the congruent angles are called the base angles and the other angle is known as the vertex angle. ∠bac and ∠bca are the base angles of the triangle picture on the left. the vertex angle is ∠abc