40 + 2x - 30 + x + 20 = 180
3x + 30 = 180
3x = 150
x = 50
m<B = 2x - 30
m<B = 2(50) - 30
m<B = 100 - 30
m<B = 70
50 is not a perfect square because it does not have a perfect square root where as 49 is 7, 121 is 11, and 1 is 1
<span>Pythagorean triple
a^2 + b^2 = c^2
so
5^2 + 12^2 = 13^2
25 + 144 = 169
169 = 169
answer is D. last one 5, 12 , 13</span>
Use the 30-60-90 triangle.
Tan is opposite over adjacent.

Square roots cannot be on the bottom.

The bottom cancel out the square root bar.
Your answer is:

(It's best to memorize the 30-60-90 and the 45-45-90 triangles during trigonometry. It helps a lot.)
Hope this helps!
:)