Find the area of an isosceles triangle with two sides being 1 and an angle A being 30 degrees.
There is a formula to find the area of a triangle for this exact situation. I will use a picture to illustrate it:
Source: http://maths.nayland.school.nz/Year_12/AS_2.4_Trigonometry/Images/Pinboard_posters/ScreenShot043.gif
In the diagram above, if we know the lengths of 2 sides of a triangle and the measure of the included angle, then the area of the triangle can be found using the formula of A△=12absinC. Now, let's apply the formula!
A△=12absinC | Plug in the the side lengths as a and b (order is immaterial) and the measure of the included angle as C. |
A△=12(1)(1)sin30∘ | Let's simplify the sin of 30 degrees. You may already be aware thatsin30∘=0.5. |
A△=12(1)(1)(0.5) | If you multiply a number by 1, the number is itself. |
A△=12(0.5) | (1/2)*0.5=1/4, or 0.25. |
A△=14units2=0.25units2 | |
I'm mildly glad that this question was answered previously because reference to ∠A is still ambiguous; ∠A can refer to ∠CAD, ∠CAB, ∠BAD.
If you want to reference an angle that has several common vertices, it is impossible to determine which angle one is referring to. Solve the problem by using 3 letters as opposed to 1. Can you please clarify which angle is indeed ∠A?
There is a formula to find the area of a triangle for this exact situation. I will use a picture to illustrate it:
Source: http://maths.nayland.school.nz/Year_12/AS_2.4_Trigonometry/Images/Pinboard_posters/ScreenShot043.gif
In the diagram above, if we know the lengths of 2 sides of a triangle and the measure of the included angle, then the area of the triangle can be found using the formula of A△=12absinC. Now, let's apply the formula!
A△=12absinC | Plug in the the side lengths as a and b (order is immaterial) and the measure of the included angle as C. |
A△=12(1)(1)sin30∘ | Let's simplify the sin of 30 degrees. You may already be aware thatsin30∘=0.5. |
A△=12(1)(1)(0.5) | If you multiply a number by 1, the number is itself. |
A△=12(0.5) | (1/2)*0.5=1/4, or 0.25. |
A△=14units2=0.25units2 | |