In ∆DEF, ∠F = ∠D and EF = 4 cm and DF = 5 cm. Then find the length of DE

DE = 4cm.

Step-by-step explanation:

The Isoscles Triangle Theorem says that:

"If two sides of a triangle are congruent, then angles opposite those sides are congruent."

The converse of this theorem is

"If angles opposite those sides are congruent, then two sides of a triangle are congruent."

Therefore, since ∠F is congruent to ∠D and are opposite sides ED and EF

while EF = 4 cm and DF = 5 cm.

DE = 4cm.

- 2 + 10x³ - 21x² + 19x - 4

step-by-step explanation:

each term in the second factor is multiplied by each term in the first factor

x²(- 2x² + 4x - 1) - 3x(- 2x² + 4x - 1) + 4(- 2x² + 4x - 1) ← distribute

= - 2 + 4x³ - x² + 6x³ - 12x² + 3x -8x² + 16x - 4

collect like terms

= - 2 + 10x³ - 21x² + 19x - 4 ← in standard form

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )