Thursday

October 23, 2014

October 23, 2014

Posted by **Kitor** on Wednesday, May 22, 2013 at 10:18pm.

I have tried to answer this in so many ways but couldn't get right answer ... Help please !

- Math calculus -
**Reiny**, Wednesday, May 22, 2013 at 10:53pmLet the base be x cm and the height be y cm

Area = (1/2)xy cm^2

dArea/dt = (1/2)(x dy/dt + y dx/dt) ------- #1

given: dy/dt = 1000 cm/min

dArea/dt = 1500 cm^2/min

find dx/dt when y = 7000 cm and Area = 89000 cm^2

...........

when y = 7000 and area = 89000

(1/2)(x)(7000) = 89000

x = 178/7

which leaves dx/dt as the only missing part of #1

1500 = (1/2)( (178/7)(1000) + 7000(dx/dt) )

3000 = 178000/7 + 7000 dx/dt

dx/dt = -157000/49000 cm/min

= - 157/49 cm/min

= appr -3.2 cm/min

At that instant, the base is decreasing at a rate of appr 3.2 cm/min

**Answer this Question**

**Related Questions**

math - The altitude of a triangle is increasing at a rate of 1500 centimeters/...

Calculus - The altitude of a triangle is increasing at a rate of 3000 ...

Calculus Please help! - The altitude of a triangle is increasing at a rate of ...

Calc - The altitude of a triangle is increasing at a rate of 2500 centimeters/...

Math - The altitude of a triangle is increasing at a rate of 2500 centimeters/...

CAL - The altitude of a triangle is increasing at a rate of 2500 centimeters/...

CAL - The altitude of a triangle is increasing at a rate of 2500 centimeters/...

calculus - The altitude of a triangle is increasing at a rate of 3.000 ...

math - The altitude of a triangle is increasing at a rate of 3 centimeters/...

math - The altitude of a triangle is increasing at a rate of 1.500 centimeters/...