# How To Justify Construction Of 90 Degree Angle?

1. Take O as centre, draw an arc cutting OP at Q.
2. Step-2: Taking Q as centre and same radius, cut arc R, then from R, cut arc S.
3. Step-3: Taking centre R and S, draw point A, taking distance more than half of RS.
4. and then join OA.
5. Hence,we have constructed right angled angle ∠POA=900.

#### How do you explain a 90-degree angle?

Right angle – When two straight lines intersect each other at 90˚ or are perpendicular to each other at the intersection, they form the right angle. A right angle is represented by the symbol ∟. The given image shows various formations of the right angle. We can find the right angles in shapes. A square or rectangle has four corners with right angles. Examples of right angles are all around us. We can see right angles in the corners of a room, book, cube, windows and at several other places. A vertical and a horizontal line makes the most common right angles. However, diagonal lines intersecting each other also form right angles.

#### What does it mean to justify a construction?

Justification of Construction: We can justify the construction, if we can prove ∠UPQ = 90°. For this, join PS and PT. We have, ∠SPQ = ∠TPS = 60°. In (iii) and (iv) steps of this construction, PU was drawn as the bisector of ∠TPS. ∴ ∠UPS = ∠TPS.

#### What is the 3 4 5 Triangle rule in construction?

The 3:4:5 triangle is the best way I know to determine with absolutely certainty that an angle is 90 degrees. This rule says that if one side of a triangle measures 3 and the adjacent side measures 4, then the diagonal between those two points must measure 5 in order for it to be a right triangle.

## Is justification necessary for construction?

is justification of construction necessary for class 10 exam 2018-19( for 4 marks) Dear Student! Yes, it is necessary to write the justification of construction. Justification is done in order to check whether the figure which we have drawn is perfect or not according to the conditions and values given in the question. Cheers! : is justification of construction necessary for class 10 exam 2018-19( for 4 marks)

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#### How do you construct an angle of 90 in math?

FAQs on Constructing an Angle of 90 Degrees – An angle of 90° is called a, Constructing an angle of 90° can be done by measuring 90° in the protractor or by constructing a perpendicular bisector to a straight line. The perpendicular bisector makes 90° with a straight line.

## How do you construct a 90 degree angle without a compass?

Download Article Download Article Often times, you are required to construct some angles without using a protractor. This article teaches you how to draw a 90 degrees angle using a compass and a ruler.

1. 1 Mark the vertex of your angle anywhere on the paper. Let us name this point as M,
2. 2 Draw a ray MN, extending in any direction and of any length. This will be one of the arms of our angle. Advertisement
3. 3 Place tip of the compass on point M and draw a circle cutting the ray MN at some point (say P).
4. 4 Keep the width of the compass the same. Then place its tip on P and draw an arc cutting the circle at some point (say Q).
5. 5 Keep the width of the compass the same. Place its tip on Q and draw another arc cutting the circle at another point (say R).
6. 6 Keep the tip of the compass still on Q. Draw another arc somewhere outside the circle. For carrying out this step, you can set the width of the compass to any measure.
7. 7 Keep the same width of the compass (as set in the previous step). Now place its tip on R and draw another arc which cuts the arc drawn in the previous step at some point (say S).
8. 8 Connect the points M and S with a straight line. Extend it to form a ray ML.
• The measure of the angle LMN is 90 O,

1. 1 Draw a straight line. On a piece of paper, draw a line segment of any convenient length. Make it horizontal for the sake of simplicity, but it could be at any angle. Label the line segment AB.
2. 2 Pick any point on AB. Mark it, and label it O. O can be anywhere on the line segment, including at either end point (A or B). For convenience, let’s put O somewhere near the middle of AB. The line segment could now be referred to as AOB.
3. 3 Grab a compass. Open the compass to a radius a little shorter than either AO or OB. Now place the compass point at O. Strike short arcs through AB on either side of O. The two arcs should have the same radius. Label those two points of intersection C and D. Now the line segment could be referred to as ACODB.
4. 4 Strike two more arcs. Place the compass point at C, and strike an arc to one side of the line segment. Then place the compass point at D, and strike a second arc of the same radius and on the same side of the line segment. Make sure those two arcs intersect. Call that point of intersection E.
5. 5 Draw the 90° angle. Draw a straight line from E to O. Line segment EO forms a 90° angle with line segment AB. It actually forms two 90° angles at O. If you were to extend EO beyond AB, you would form four 90° angles at O.
• Note that you can draw a 90° angle at either end of line segment AB if you want to (in other words at point A or point B). Simply extend AB beyond A or beyond B, and then follow the above steps. Point A (or point B) would serve as point O in the above instructions.
• This is essentially the same method featured in How to Construct a Perpendicular Line to a Given Line Through Point on the Line, Method 2,

• Question How do I draw a right angle triangle? First construct a 90° angle as shown above. Extend each leg of the angle any convenient length. Draw a line from the end of one leg to the end of the other. You have a right triangle.
• Question How do I construct a 15 degree angle? First, make a 60 degree angle by constructing an equilateral triangle. Use angle bisection construction to make a 30 degree angle. Bisect the 30 degree angle again to make a 15 degree angle.
• Question Can I draw a 133-degree angle? There is no way to construct such an angle using a compass and a ruler. That’s why they invented the protractor.

• Paper
• Pen or pencil
• Ruler or another straightedge
• Compass

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#### Why is 90 degrees called a right angle?

Why is a 90 degree angle called a ”right” angle, why not ”left” or ”wrong”? | Notes and Queries | guardian.co.uk

• Why is a 90 degree angle called a ‘right’ angle, why not ‘left’ or ‘wrong’?
• Because it is the correct angle required for many construction tasks – laying out buildings etc. Along similar lines there is a species of whale which is called the “Right Whale”, simply because it was the right whale to hunt if you wanted to make maximum profits.
1. Simon Blake, Shrewsbury England
• Simon Blake’s answer sounds a bit like a guess. A right angle would be “wrong” for just as many tasks. Right, meaning “correct”, and right, meaning “straight”, do have the same root, but “right angle” derives from the second rather than the first. A right angle was described in ancient geometry as the meeting of two right, ie straight, lines, with regard to dimensional axes.
• Michael Cullen, Dublin

: Why is a 90 degree angle called a ”right” angle, why not ”left” or ”wrong”? | Notes and Queries | guardian.co.uk

## How do you introduce students to their angles?

Tape random straight lines across students’ tables to create lots of angles where the tape overlaps. Then ask your students to sit around the table with a marker, and encourage them to classify as many angles as they could. After classifying angles, your pupils can then move on to measuring them.

## What is the rule for right angles?

One angle is always 90° or right angle. The side opposite angle of 90° is the hypotenuse. The hypotenuse is always the longest side. The sum of the other two interior angles is equal to 90°.

#### Why is it called a 90-degree angle?

Why is a 90 degree angle called a ”right” angle, why not ”left” or ”wrong”? | Notes and Queries | guardian.co.uk

• Why is a 90 degree angle called a ‘right’ angle, why not ‘left’ or ‘wrong’?