WP5a
Practice - Angles and Triangles
TRY TO ANSWER IN TWO AND A HALF MINUTES.
QUESTIONS
QUESTIONS
1. What is the sum of the angles in a rectangle? In a triangle?
2. What is an isosceles triangle?
3. When the hour hand of a clock has moved 60 degrees, how much time has elapsed?
4. One corner of a triangle measures 38 degrees, and a second corner measures 56 degrees. What does the third corner measure?
5. What do you call a triangle with two equal sides?
6. An isosceles triangle has equal angles of x degrees and an unequal angle of y degrees. Write an equation for x.
7. A parallelogram has two acute angles and two obtuse angles. One of the obtuse angles is 110 degrees. What is the size of the acute angles?
ANSWERS
1. There are 90 degrees in each corner, for a total of 360 degrees. There are 180 degrees in any triangle.
2. A triangle with two equal sides. The two sides are called legs; the other side is called the base.
3. There are 360 degrees in the complete circle. 60 degrees would be 1/6, of this. 1/6 of 12 hours is two hours. You can also see that a 90-degree movement would be from 12 o'clock to 3 o'clock, or three hours. So the answer would be 2/3 of that, or 2 hours.
4. The sum of the angles of any triangle is 180 degrees. So the third corner is 180 degrees minus 38 degrees minus 56 degrees, or 86 degrees.
5. An isosceles triangle. Two of the three angles will also be equal.
6. Any triangle's angles total 180 degrees. The expression is 2x + y = 180, so x = (180 - y)/2.
7. The total of the four angles is 360 degrees. Each pair of acute and obtuse angles totals 180 degrees. If one angle is 110 degrees, the other angle is 180 degrees minus 110 degrees, or 70 degrees. Notice that you don't have to understand the definitions of acute and obtuse angles to answer this question.