JB Geometry Formulae

Question 1

Ar of eq triangle of side a

Answer 1

(√3 x a^2) /4

Question 2

30° - 60° - 90° sides ratio

Answer 2

1 : √3 : 2

Question 3

45° - 45° - 90° sides ratio

Answer 3

1 : 1 : √2

Question 4

triangle abc ~ triangle efg, ratio of side

Answer 4

ab/ef = bc/fg = ca/ge = h1/h2 = k

Question 5

triangle abc ~ triangle efg, ratio of area

Answer 5

ar(abc)/ ar(efg) = (ab)^2 / (ef)^2 = k

Question 6

ar of trapezoid

Answer 6

1/2 x (sum of //el sides) x (distance b/w //el sides)

Question 7

Area of parallelogram

Answer 7

base x height

Question 8

Area of rhombus

Answer 8

1/2 x diagonal 1 x diagonal 2

Question 9

Ar of rectangle

Answer 9

length x width

Question 10

Area of sqaure

Answer 10

side ^ 2
or
1/2 x diagonal^2

Question 11

sum of interior angles of polygon of side n

Answer 11

180° x (n-2)

Question 12

num of diagonals in polygon of side n

Answer 12

[ n x (n-3) ] / 2

Question 13

length of arc of circle with angle x

Answer 13

( x / 360 ) x 2 x pi x r

Question 14

length of arc of circle with angle x

Answer 14

( x / 360 ) x 2 x pi x r

Question 15

length of arc of circle with angle x

Answer 15

( x / 360 ) x 2 x pi x r

Question 16

ratio of angle at center: angle on any point on circle from two points A & B

Answer 16

2 : 1

Question 17

diagonal of 3d rectangular solid

Answer 17

d = √( l^2 + b^2 + h^2)

Question 18

vol of 3d rectangular solid

Answer 18

lbh

Question 19

TSA of 3d rectangular solid

Answer 19

2(lb+bh+hl)

Question 20

diagonal of 3d cube

Answer 20

√3 x a

Question 21

vol of 3d cube

Answer 21

a^3

Question 22

TSA of 3d cube

Answer 22

6 x a^2

Question 23

vol of right circular cylinder

Answer 23

pi x r^2 x h

Question 24

CSA of right circular cylinder

Answer 24

2 x pi x r x h

Question 25

TSA of right circular cylinder

Answer 25

2 x pi x r (r +h)

Question 26

slant height (l) of right circular cone

Answer 26

√( r^2 + h^2)

Question 27

vol of right circular cone

Answer 27

1/3 x pi x r^2 x h

Question 28

CSA of right circular cone

Answer 28

pi x r x l

Question 29

TSA of right circular cone

Answer 29

pi x r x ( l +r )

Question 30

vol of sphere

Answer 30

4/3 x pi x r^3

Question 31

TSA of sphere

Answer 31

4 x pi x r^2