The length of the missing sides

length-14cm width-7cm

Step-by-step explanation:

To work out the sides, you can use 2l+2w=42. Since the length is twice the width, this becomes 2(2w)+2w=42.

This can be expanded to 4w+2w=42 or 6w=42.

From there, we can divide both sides by 6 to isolate w, meaning w=7.

Since the length is twice the width, it is given by l=2×7 or l=14.

**This question involves writing and solving algebraic equations from worded questions, which you may wish to revise. I'm always happy to help!

1. 180°. the sum of the interior angles of a triangle is 180°, for the equilateral triangle that it has three equals side is 60°+60°+60°=180°.

2. 60°. each interior angle of a equilateral triangle is 60°

3. 120°. the measure of ∠m is 120°, the sum of the angles ∠m and ∠n is equal to 180°. so, in order to find the measure of ∠m, we have ∠m+∠n=180° > ∠m=180°-∠n > ∠m=180°-60°=120°.

4. 360°. the sum of the exterior angles of an equilateral triangle is ∠m+∠r+∠x=120°+120°+120°=360°. the exterior angles of any triangle always add 360°.