Lesson 2: Square Roots of Non­Perfect Squares
What are the first 5 perfect square whole numbers?
What are the square roots of these numbers?
Which numbers are between these perfect squares?
What do you think their square roots will be?
1
A ladder is leaning against a wall, for safety the distance from the base of the ladder to the wall must be about 1/4 of the height up the wall. A ladder is 2 m from the wall how high up will the ladder reach for it to be safe?
Need ladder picture How can you check how long the ladder is if you are only given the height along the wall and the distance away from the wall?
2
A ladder is 6.1m long. the distance from the base of the ladder to the wall is 1.5m. Estimate how far up the ladder will reach.
What is your strategy for estimating? (work in groups of 2­3 to find more then one way of finding the height. 3
Strategies for estimating non perfect squares
1. using number line benchmarks
2. Using a calculator. 4
Assignment
Pg. 18­20 , # 4­5 odds, 6­8, 9 odds, 10, 11 efgh, 12 ac, 13, 15, 16a, 17cd, 19 ab, 20a, 21a. 5
1. Determine an approximate value of each square root.
a) √(8/5)
b)√(3/10)
c) √(3/7)
d) √(19/6)
2. Identify a decimal that has a squaroot between 9 and 10.
Check your answer.
3. The sloping face of a ramp is to be covered in carpet.
a) estimate the length of the ramp to the nearest tenth of a
meter.
b) use a calculator to check the answer.
c) calculate the area of carpet needed.
2.5 m 2.6 m
7.5 m 6