Drawing Angles
Vidya wants to draw a 30° angle and name it ∠TIN using a protractor. In ∠TIN Ibe the vertex, IT and IN will be the arms of the angle. Keeping one arm, say IN, as the reference (base), the other arm IT should take a turn of 30°.
Step 1: We begin with the base and draw 𝐼𝑁:
Step 2: We will place the centre point of the protractor on I and align IN to the 0 line.
Step 3: Now, starting from 0, count your degrees (0, 10, 30) up to 30 on the protractor. Mark point T at the label 30°.
Step 4: Using a ruler join the point I and T. ∠TIN = 30° is the required angle.
Let’s Play a Game 1
This is an angle guessing game! Play this game with your classmates by making two teams, Team 1 and Team 2. Here are the instructions and rules for the game:
• Team 1 secretly choose an angle measure, for example, 49° and makes an angle with that measure using a protractor without Team 2 being able to see it. • Team 2 now gets to look at the angle. They have to quickly discuss and guess the number of degrees in the angle (without using a protractor!). • Team 1 now demonstrates the true measure of the angle with a protractor. • Team 2 scores the number of points that is the absolute difference in degrees between their guess and the correct measure. For example, if Team 2 guesses 39°, then they score 10 points (49°–39°). • Each team gets five turns. The winner is the team with the lowest score!
Let’s Play a Game 2
We now change the rules of the game a bit. Play this game with your classmates by again making two teams, Team 1 and Team 2. Here are the instructions and rules:
• Team 1 announces to all, an angle measure, e.g., 34°. • A player from Team 2 must draw that angle on the board without using a protractor. Other members of Team 2 can help the player by speaking words like ‘Make it bigger!’ or ‘Make it smaller!’. • A player from Team 1 measures the angle with a protractor for all to see. • Team 2 scores the number of points that is the absolute difference in degrees between Team 2’s angle size and the intended angle size. For example, if player’s angle from Team 2 is measured to be 25°, then Team 2 scores 9 points (34°–25°). • Each team gets five turns. The winner is again the team with the lowest score.
Figure it Out
1. In the figure, list all the angles possible. Did you find them all? Now, guess the measures of all the angles. Then, measure the angles with a protractor. Record all your numbers in a table. See how close your guesses are to the actual measures._
All angles: ∠
2. Use a protractor to draw angles having the following degree measures:
a. 110° b. 40° c. 75° d. 112° e. 134°
3. Draw an angle whose degree measure is the same as the angle given below:
Also, write down the steps you followed to draw the angle.