Answer 420.
a, is the first term. d is difference.
Since this is an arithmetic progression, I use this formula.
Un = nth term
Sn = sum of terms.
First find the number of terms, which is 20.
Then use the second formula to find the sum.
I'm guessing that you know about 45-45-90 and 30-60-90 triangles.
In 45-45-90 triangles, the legs are in a ratio such that the hypotenuse is
times the legs.
In 30-60-90 triangles, the legs are in a ratio of 1:
:2
In the picture given we have been given a value of the side of the 45-45-90 triangle. We can deduce that the value of the hypotenuse is 9
because of the ratio of the sides of a 45-45-90 triangle.
The 30-60-90 triangle shares the same hypotenuse, and so we now know a value of one of its sides as well. The ratio of the side of value 'x' and the hypotenuse is
: 2
We can create an equation to solve for x using these ratios:
= 
Cross multiply:
2x = 9
x = 
Option C
11.6 rounded to the nearest whole is 12 and 4.1 rounded to the nearest whole is 4 (rule is if the decimal [or number in general] is 4 or lower, the whole stays the same and if the number is 5 or higher, the whole goes up by one). 12+4=16
Answer:
Step-by-step explanation:
Area is base times height. Parallelogram area/3
triangle area/4
Student is wrong An exterior angle of a triangle can be adjacent to the right angle of a right triangle, so an exterior angle can be a right angle.
<h3>What is exterior angle?</h3>
The Exterior Angle is the angle between any side of a shape, and a line extended from the next side.
The student make an error he states that the exterior angle of a triangle can never be a right angle.
The correct answer will be option D that is An exterior angle of a triangle can be adjacent to the right angle of a right triangle, so an exterior angle can be a right angle.I have also attached the diagram of the triangle for better understanding.
To know more about exterior angle follow
brainly.com/question/2546141
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