How is this 90 degrees?

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In summary, a 90 degree angle is formed when two lines intersect at a right angle, measuring 90 degrees. It can be measured using a protractor or by knowing the sum of angles in a triangle. 90 degree angles have significance in geometry and are used in construction and engineering. Real-world examples include building corners, road intersections, and shapes like squares and rectangles. In trigonometry, a 90 degree angle is used to define the right triangle and is essential in calculations such as the Pythagorean theorem.
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Joza
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http://www.e-xamit.ie/2005test/php/GetDocByID.php?id=562&prep=565&soln=562&tip=570&port=566 [Broken]


I can't figure out how it takes the angle dec to be 90 degrees? How?
 
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Line segment ce is parallell to line segment ab. Line segment ad is perpendicular to ab at a, hence, ad is perpindicular to ec at e.
 
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I am unable to provide a response to this content as it is not clear what specific angle or measurement is being referred to. In order to accurately determine how an angle could be 90 degrees, more information and context would be needed. Additionally, this appears to be a link to an online test, which may not be a reliable or accurate source of scientific information.
 

1. What does it mean for something to be at a 90 degree angle?

Being at a 90 degree angle means that two lines intersect to form a right angle, where both lines are perpendicular to each other and measure 90 degrees.

2. How do you measure a 90 degree angle?

A 90 degree angle can be measured using a protractor or by using the fact that the sum of the angles in a triangle is 180 degrees, so a right angle would be half of that (90 degrees).

3. What is the significance of a 90 degree angle?

A 90 degree angle is significant in geometry and mathematics as it is one of the basic angles that is used to form other shapes and angles. It is also used in engineering and construction to ensure stability and precision in structures.

4. What are some real-world examples of a 90 degree angle?

Some common examples of a 90 degree angle in the real world include the corners of buildings, the intersection of two roads, and the edges of a book or paper. Other examples include the hands of a clock at 3 and 9 o'clock, and the shape of a square or rectangle.

5. How is a 90 degree angle used in trigonometry?

In trigonometry, a 90 degree angle is used to define the right triangle, which is the basis for many trigonometric functions and calculations. It also helps in determining the relationship between the sides and angles of a triangle, known as the Pythagorean theorem.

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