What we know is that the sum of a triangle's internal angles are 180º, and a straight angle makes 180º.
first, we have to find the third internal angle(let's call it n) so that we can use it to find the exterior angle.
(3x + 20) + (4x + 5) + n = 180
simplify:
7x + 25 + n = 180
7x + n = 155
n = 155 - 7x
Now we can add it to the external angle to find x.
(155 - 7x) + (8x + 15) = 180
simplify:
170 + 8x - 7x = 180
170 + x = 180
x = 10
Now we can substitute it to the external angle.
8 x 10 + 15 = 95
the exterior angle is 95º.
The blank spaces in the task content can be filled with; Substitution property, 90° and subtraction property.
<h3>What are the missing statements in the proof?</h3>
Since it follows from the vertical angles theorem that angle 1 = angle 4 as they are congruent.
Additionally, angles 1 and 2 are said to be complementary and hence, the sum of their measures is equal to 90°.
Finally, by virtue of the subtraction property of equality, the measure of angle 2 is; 90° - 40° = 50°.
Read more on complementary angles;
brainly.com/question/16281260
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Answer:
Option A
fraction numerator square root of 2 over denominator 2 end fraction
Step-by-step explanation:
The answer can be obtained using a calculator.
It corresponds to a notable identity
sin (45) = 
/ 2
sin (45) = 0.7071
/ 2 = 0.7071
Please see attached picture
