ABC and ACD are triangles
a) Show that AC=11.4cm, correct to 3 significant figures.

17² + 13² - 2 × 17 × 13 × COS(42) = 11.38112416

AC = 11.38112416 correct to 3 significant figures = 11.4cm

Thanks for helping me on part B :)

Step-by-step explanation:

infinitely many solutions

step-by-step explanation:

we have been given the equation;

2(2x + 3) = -4 + 2(2x + 5)

we need to determine the value of x.

2(2x + 3), we expand this expression to obtain 4x + 6

similarly 2(2x + 5) will become 4x + 10

now we have;

4x + 6 = -4 + 4x + 10

4x + 6 = 4x + 10 - 4

4x + 6 = 4x + 6

the expression on the left hand side is identical to the one on the right hand side. therefore, we are looking at just a single straight line whose equation is;

y = 4x + 6

consequently, we shall have infinitely many solutions

i dony know

step-by-step explanation: