Question

On a piece of paper, use a protractor and a ruler to construct △ABC with AB=4 in., AC=4 in., and m∠A=60°.

Which statement is true about this triangle?


BC=3 in.

BC=4 in.

BC=5 in.

The length of BC¯¯¯¯¯ cannot be measured.

Answer 1

bc = 4

Explanation:

Answer 2

BC 4 in

Explanation:

The steps for construction;

• Using a ruler draw line AB 4 inches and label the end points A and B
• At point A , using a protractor, measure angle 60° and mark with point. Draw a line from A passing through this point extending to a length of 4 inches
• Mark that point C.
• Using the ruler, join point C and B and measure BC.

From calculation, length BC can be found by the formula;

`BC=√(a^2+b^2-2*a*b*cosA)`------where a=b=4 in , cos A = cos 60°

`BC=√(4^2+4^2-2*4*4*cos60)`

BC = 4 in