Medical researchers have determined that for exercise to be beneficial, a person’s desirable heart rate, R, in beats per minute, can be approximated by the formulas
for men,

where a represents the person’s age. If the desirable heart rate for a man is 135 beats per minute, how old is he?
a.
22.5 years old
b.
40 years old
c.
45 years old
d.
42.5 years old

It’s B

80 the answer is 80

step-by-step explanation:

step-by-step explanation:

this can be solved first with pythagorean theorem, which tells us to square both legs of the triangle and sum it. this will be equal to the square of the hypotenuse.

the hypotenuse is the side "opposite" the 90 degree angle, which is x.

so we can write using pythagorean theorem,

simplifying:

to further simplify this radical, we need to use the property  

thus

oh

nu stiu chiar nu stiu sa o fac

one triangle is 2.5 times bigger than the other triangle.