From left, a lens labeled 1 flat on the left and convex on the right, a thick lens labeled 2 double convex, a lens labeled 3 convex on the right and slightly concave on the left, a lens labeled 4 flat on the left and concave on the right, a lens labeled 5 concave on both left and right, a thin lens labeled 6 double convex.
Which lenses are convex? Check all that apply.

1
2
3
4
5
6

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y

3. dark matter

empty space could also be a simple vacuum

the answer is c. the lower legs are levers, and the knees are fulcrums. the ankles hold the loads.