McGraw Hill Glencoe Geometry, 2012
MH
McGraw Hill Glencoe Geometry, 2012 View details
4. Volumes of Prisms and Cylinders
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Exercise 38 Page 868

Use some simple solids, like rectangular prisms.

Example Solution:

Practice makes perfect

We are asked to sketch and label in inches three different designs for a measuring cup that holds 1 cup, which is about 14.4375 cubic inches. We could make this cup be a pyramid with some sophisticated base, like below.

However, then there will be a lot of computations to find the exact dimensions of such a cup. Let's make it simple and find measuring cups in the shape of a rectangular prism. We choose this shape because the volume of a rectangular prism is equal to the product of its dimensions, but keep in mind that there are many different solutions to this problem.

Option 1

First, let the measuring cup be in the shape of a cube and s be its side length. Then its volume is V=s^3. We know that the volume of the cup has to be about 14.4375 cubic inches. Let's find s!

V=s^3
14.4375=s^3
â–¼
Solve for s
sqrt(14.4375)=s
s=sqrt(14.4375)
s≈ 2.43499
s≈ 2.43

Therefore, the side length of the cube should be about 2.43 inches. Now, let's sketch the cube!

Option 2

Now let the measuring cup be in the shape of a square prism with a side base length of 2 inches. Let h denote its height. Then its volume is V=2* 2* h=4h. We know that the volume of the cup has to be about 14.4375 cubic inches. Let's find h!

V=4h
14.4375=4h
â–¼
Solve for h
3.60938=h
h=3.60938
h≈ 3.61

Therefore, the height of the prism should be about 3.61 inches. Now, let's sketch the prism!

Option 3

Now let the measuring cup be in the shape of a square prism with a side base length of 3 inches. Let h denote its height. Then its volume is V=3* 3* h=9h. We know that the volume of the cup has to be about 14.4375 cubic inches. Let's find h!

V=9h
14.4375=9h
â–¼
Solve for h
1.60417=h
h=1.60417
h≈ 1.60

Therefore, the height of the prism should be about 1.6 inches. Now, let's sketch the prism! <jsxgpre id="Solution41761_4" static=1> var b = mlg.board([-2.5, 12.5, 18.5, -2.5], {desktopSize:'medium', style:'usa'});



/* %% Length of a Vector - Array */ function myLength(vec){ return Math.sqrt(vec[0]*vec[0]+vec[1]*vec[1]); }

/* Crearing a right angle from three points - in Perspective Geometry is helpful*/ function myRightAngle(p_1,p_2,p_3,len){ var temp1X = p_2.X() + len*(p_1.X()-p_2.X())/myLength([p_2.X()-p_1.X(),p_2.Y()-p_1.Y()]);

   var temp1Y = p_2.Y() + len*(p_1.Y()-p_2.Y())/myLength([p_2.X()-p_1.X(),p_2.Y()-p_1.Y()]);
   var temp3X = p_2.X() + len*(p_3.X()-p_2.X())/myLength([p_2.X()-p_3.X(),p_2.Y()-p_3.Y()]);
   var temp3Y = p_2.Y() + len*(p_3.Y()-p_2.Y())/myLength([p_2.X()-p_3.X(),p_2.Y()-p_3.Y()]);
   var temp2X = temp1X+temp3X-p_2.X();
   var temp2Y = temp1Y+temp3Y-p_2.Y();
   var node_temp1 = b.node(temp1X,temp1Y);
   var node_temp3 = b.node(temp3X,temp3Y);
   var node_temp2 = b.node(temp2X,temp2Y);
   b.segment(node_temp1,node_temp2,{strokeColor:'red',strokeWidth:1});
   b.segment(node_temp3,node_temp2,{strokeColor:'red',strokeWidth:1});

}

/* %%%%%%%%%%% Find a geometric middle of an array of pts %%%%%% %%%% Returns an array of two values %%%%% */ function myMiddle(p_arr){ var n_temp = p_arr.length;

   var sumX = 0;
   var sumY = 0;
   for(var ii=0; ii<n_temp; ii++){
   	sumX = sumX + p_arr[ii].X();
       sumY = sumY + p_arr[ii].Y();
   }
   return [sumX/n_temp, sumY/n_temp];

}

/* %%%%% create a segment between two points, type=0 gives a solid one, type=1 a dashed usual one (Zwierz) %%%% */ function mySegment(p_1,p_2,type){ if(type==0){ b.segment(p_1,p_2,{strokeWidth:1.5,dash:0});}

   if(type==1){ b.segment(p_1,p_2,{strokeWidth:1,dash:2});}

}

/* %%%%% MEASURES %%%%%% */ function myMeasure(p_1,p_2,gap_,dist_,text_){ b.measure(p_1,p_2,{centerGap:gap_,legs:{strokeWidth:1,dash:2,length:dist_,strokeColor:'black'},label:{text:text_,anchor:0.5,mathMode:true,distance:0,rotate:false,position:'middle',precision:0,fontSize:0.9}}); }

var hi = 4.4-1.5; var len = 1.2;

var p1 = b.node(0,0); var p2 = b.node(4.8,0); var p3 = b.node(4.8+2*len,len); var p4 = b.node(2*len,len);

var q1 = b.node(p1.X(),p1.Y()+hi); var q2 = b.node(p2.X(),p2.Y()+hi); var q3 = b.node(p3.X(),p3.Y()+hi); var q4 = b.node(p4.X(),p4.Y()+hi);

mySegment(p1,p2,0); mySegment(p2,p3,0); mySegment(p3,p4,1); mySegment(p4,p1,1);

mySegment(q1,q2,0); mySegment(q2,q3,0); mySegment(q3,q4,0); mySegment(q4,q1,0);

mySegment(p1,q1,0); mySegment(p2,q2,0); mySegment(p3,q3,0); mySegment(p4,q4,1);

var front_face = b.polygon([p1,p2,q2,q1],{borders:{visible:false},fillColor:'#b3f0cb'}); var right_face = b.polygon([p2,p3,q3,q2],{borders:{visible:false},fillColor:'#b3f0c0'}); var top_face = b.polygon([q1,q2,q3,q4],{borders:{visible:false},fillColor:'#aabb00'});

b.gradient(front_face,{color:[mlg.tikzColor('darkorange!30'),"darkorange"],radial:true,cx:10,cy:10,r:100}); b.gradient(top_face,{color:[mlg.tikzColor('darkorange!30'),"darkorange"],radial:true,cx:10,cy:50,r:100}); b.gradient(right_face,{color:[mlg.tikzColor('darkorange!80'),"darkorange"],radial:true,cx:10,cy:50,r:100});

myMeasure(p1,p2,0.2,-1.5,'3'); myMeasure(p2,p3,0.4,-1.5,'3'); myMeasure(q1,p1,0.3,-2,'1.6');

myRightAngle(p4,p1,p2,0.7); myRightAngle(p1,p2,p3,0.7); myRightAngle(p2,p3,q3,0.7); myRightAngle(p3,q3,q2,0.7);

b.txt(3.8,5,'(\\text{inches})');

b.trim(); </jsxgpre>