Question

Draw a right triangle that has an 18-cm hypotenuse and a 70-degree angle. To within 0.1 cm, measure the leg adjacent to the 70-degree angle, and express your answer as a percentage of the hypotenuse. Compare your answer with the value obtained from your calculator when you enter COS 70 in degree mode. This is an example of the

Answer 1

`(6.3cm)/(18cm)=0.35`

or 35%

cos(70°)=0.34

The difference in the result is because of the precision of the measurements.

Explanation:

First, we can start by drawing a horizontal line in our sheet of paper and pick one point on the line. (Picture 1)

Next we take our protractor and measure 70°. (Picture 2)

Then we draw a line that measures 18cm with our ruler from the point we selected on the horizontal line to the point we measured with the protractor. (Picture 3)

Next we take our square and measure a 90° angle from the end of the line we drew on the previous step to the horizontal line and connect the horizontal line to the ending point of the hypotenuse. (Picture 4)

And that will be our triangle. Next we can measure the adjascent side to the 70° angle (Picture 6) which turned out to be 6.3cm which can now be used to calculate the ratio as a percentage. (Picture 5)

`ratio=(adjascent)/(hypotenuse)=(6.3cm)/(18cm)=0.35`

which is the same as a 35%.

If we calculated the cos(70°) with our calculator we would get:

cos(70°)=0.34

As you may see our measurements were pretty precise, the difference in answers will depend on the precision of our measurements.