Video: KS2-M19 • Paper 2 • Question 13

Here is a sketch of a triangle. It is not drawn to scale. Draw the full-size triangle accurately below. Use an angle measurer (protractor) and a ruler. One line has been drawn for you.

05:18

Video Transcript

Here is a sketch of a triangle. It is not drawn to scale. Draw the full-size triangle accurately below. Use an angle measurer — sometimes called a protractor — and a ruler. One line has been drawn for you.

Now, in the diagram, we can see that the baseline needs to be eight centimeters long. This angle is a right angle. It’s 90 degrees. And this angle needs to be 35 degrees. Now, they’ve given us a start because this line here is eight centimeters long. When you print this question out to do on a piece of paper, make sure you measure the length of that line and make sure that it is eight centimeters. If you don’t print this at 100 percent scale, then you’ll find that your answer will look slightly different to our answer.

Now, I would recommend drawing a little notch like this at each end of the line. That’s gonna make it easier for us to use our protractor. First, let’s look at how we can use our protractor to create an angle of 35 degrees here. This black line going between zero degrees and zero degrees on your tractor is called the baseline of the protractor. And this vertical line going up to 90 degrees here makes a little crosshair target.

Place the protractor down very carefully so that the baseline of the protractor lines up perfectly with the eight-centimeter baseline we were given in the question. Also, make sure that the crosshair that we talked about lines up perfectly with that little notch that we drew at the left-hand end of the line. With those two things very carefully lined up, you’ll notice that we’ve got two sets of numbers on our scale.

We can either start counting from zero degrees upwards in this direction on the outer scale or zero degrees upwards in this direction on the inner scale. If we look back at our sketch, this is the sort of angle we want to make at the left-hand end. So on our protractor, we’re gonna start at zero from here and count up 35 degrees in this direction. If we go up to 30, we get to here. And then, we notice that this bit of the scale has got 10 little markings. Each one of those is one degree. So 35 degrees is this mark here. Carefully mark that off with your pencil.

It’s a good idea to look directly down onto the piece of paper above the angle when you’re marking it and to have a nice, sharp pencil to get this as accurate as you can. For the next bit, we’re going to put our pencil at this point here on this end of the line. And we’re going to draw a line that goes up through this mark here. Because the angle on the right is 90 degrees, it’s helpful to imagine a dotted line going straight up from that point. And when we draw our line, we need to make sure that it’s gonna extend far enough so that it goes beyond that imaginary dotted line.

So take your protractor away. Put your pencil point here. Bring the ruler up so that it touches that point. And then swivel it round so that it lines up with the mark that you’ve made earlier at 35 degrees. Now, you can join the two up and extend the line off as we said. The result should look something like this. Now, we’re going to need to bring our protractor back and line the crosshair up with the other end of the line so that we can measure our angle of 90 degrees.

Again, take care to make sure that the baseline of the protractor lines up perfectly with the baseline that we were given in the question and that the crosshair on your protractor lines up perfectly with the right-hand end of the line and the little notch that you made on it. Again, looking back at the sketch, we can see that this time we want to draw our angle in this direction. So we’re going to start with this zero on the scale and work our way up on the outer set of numbers until we reach 90. Then, we can carefully mark off at 90 degrees a little notch on the paper.

Again, use a sharp pencil and look directly down onto your protractor to make this as accurate as you possibly can. Next, we’re going to take the protractor away and join this end of the line here to draw a line through this notch we just created up here. Place your pencil firmly here on the paper. Slide the ruler up until it touches it. And then, swivel it round until it’s in line with the notch that you made. Carefully checking that those two things are still lined up, we can now draw in this line.

When you’re finished, your triangle should look something like this. It’s worth checking with your protractor that this angle is definitely 35 degrees and this angle is 90 degrees. If you’ve drawn everything accurately, then this side here should be about 5.6 centimeters and this side here should be about 9.8 centimeters. And this is what our final answer should look like. And remember the question didn’t ask you to check the 9.8- or the 5.6-centimeter dimensions. We’ve just included those to help you check whether you got your answer right.

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