english task

Name : Soleh uzain NIM : 11301241018 1. Pentagonal ABCDE and pentagoanal FGHIJ are congruent, if EA= 2cm, determaint length of sides FG, GH, HI, IJ. And the perimeter of pentagonal FGHIJ. solution : the corresponding sides are AB coresponds with FG, BC coresponds with GH, CD coresponds with HI, DE coresponds with IJ , EA coresponds with Fj, because pentagonal ABCDE and pentagonal FGHIJ are congruent, so the length of AG = FJ 2 = 3x – 1 3 = 3x x = 1 now we know the value of x, and we put in the other line. The length of FG = 2x +1 = 2 + 1= 3 cm The length of GH= 2x -1 = 2 - 1= 1 cm The length of IJ = x = 1 cm The length of HI =√(4+1) = √5 So the perimeter of pentagonal FGHIJ are 2 + 3 + 1 +1+√5 = 7√5 cm Source :Mathemathics for junior high school year IX, exercise page 13 number 2   2. Show the couples of the triangle are congruent Solutions: The corespondens side are GH coresponds with JK, HI coresponds to KL, and IJ coresponds with LJ. The coresponding angle are ∠JKL corespondens to ∠GHI, ∠KLJ coresponds with ∠HIG, and ∠LJK coresponds to ∠IGH, Known that JK parallel with GH, the result ∠JKL = ∠GHI. And ∠KLJ = ∠GIH (Right angle) and in this picture show the length of LK = the length of IJ. So far we have been obtained : ∠JKL = ∠GHI ∠KLJ = ∠HIG KL = HI The three situations above fulfil the requirments (angle, angle, side) so that ∆JKL ≡ ∆GHI Source : Mathemathics for junior high school year IX, exercise page 25 number 1 3.
A man with 175 cm high stands on the distance of 12 m from the telephone pole. If the length of the man’s shadow is 3 m, determine thye height of the telephone pole. Solution A man height is 175 cm, the length of the man shadow is 300 cm, distance of a man and telephone pole 1200cm, The height of the man coresponds to the hight telephone pole, And the length of the men’s shadow coresponds with distance betwen a man and telephone pole, so that proportion the coresponding sides is : (the height a man)/(the height of the telephone pole) = (the length of the men’s shadow )/(distance betwen a man and telephone pole) Let, the hight telephone pole is x cm, so by using the proportion in similiary, we get 175/x = 300/1200 300x = 1200 x 175 300x = 210000 X = 700 So the height of the telephone pole is 700 cm (7m) Source : Mathemathics for junior high school year IX, exercise page 45 number 5 4. A tree has its shadow of 1 m long on a plain surface, if the pillar with 20m high has shadow of 10 m long, determine height of the tree Solution A tree has shadow 1m, the length of the pilar shadow is 10m, the height of pillar 20m. The height of the tree has shadow coresponds to the length of the pilar shadow, And the height of pillar coresponds with the height of the tree, so that proportion the coresponding sides is : (the height of the tree)/(the height of pillar ) = ( The height of the tree has shadow )/(the length of the pilar shadow) Let, The height of the tree is y cm, so by using the proportion in similiary, we get y/20 = 1/10 10y = 20 y = 2 So the height of pillar is 2m. Source : Mathemathics for junior high school year IX, page 25 exercise number 2 5. Mrs. Tuti will make a ceremonial dish of yellow rice served in a cone shape . it has a height of 56 cm and base radius of 42 cm. Determine the volume of the dish made by Mrs. Tuti. Solution Known : the height of cone : 56cm Radius : 42cm. We know that the formulas volume of cone is 1/3x cone base area x cone height So volume = 1/3 x πr^2x t = 1/3x 22/7 x 42 x 42x 56 = 44 x 42 x 56 = 103.488 cm3 So the volume of yellow rice is 103.488 cm3 Source : Mathemathics for junior high school year IX, exercise page 73 number 2