5.-10. 20.-40 determine if arithmetic, geometrical or neither

Geometric progression.

Step-by-step explanation:

I suppose you mean this equation:

5, -10, 20, -40, ...

For a geometric progression, an n^th term is given by:

= × r

Where a is the first time, n is the term and r is the common ratio.

The common ratio here is -2 .

For instance to check the forth term;

= × -2  = 20 × -2 = -40

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐