The height of a tree in 2013 is 300% of the height it was in 2003. By what percentage did
its height increase over this ten-year period?

according to the triangle sum theorem, all the angles in a triangle must add up to 180 degrees. if we know one angle is already 90, we do 180-90=90. the other 2 angles must add up to 90, exactly.

step-by-step explanation:

thus, the first answer choice, y = sec x, is the correct one

m∠abd = m∠dbc

step-by-step explanation:

given : ab bisects ∠dbc

as we know that bisection means ab divides   ∠dbc   in two equal angles named as   ∠dba and   ∠abc

so, m∠abd = m∠dbc  

because ab bisects ∠dbc.

hence , the first statement m∠abd = m∠dbc is true.