A 30 foot ladder needs to reach 18 feet high against a building. What would the approximate angle of elevation be from the ground?

The angle of elevation would be 36.87 degrees (approximately)

Step-by-step explanation: Please refer to the attached diagram for details

The 30-foot ladder reaches a point in the building which is point A. The height at which the ladder touches the building is 18 feet (that is, the height of the building, line AC. The angle of elevation from the ground is at angle B, the angle which the ladder forms with the ground.

So we have a right angled triangle ABC, with two sides and a reference angle B. To find angle B, we shall apply the trigonometric ratio;

SinB = opposite/hypotenuse

SinB = 18/30

SinB = 0.6

By use of a calculator or table of values

B = 36.8698

Approximately, angle B = 36.87 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

the answer is a if my teacher taught me correct