E Math Reminders

Question 1

Centre and cicumference

Answer 1

Angle at center is twice angle angle at circumference

Question 2

Semicircle

Answer 2

Angle in semicircle is 90, must pass thru centre

Question 3

Same segment

Answer 3

Angles in same segment are equal (the small semicircle not the pizza slice)

Question 4

Opposite segments

Answer 4

Angles in opposite segments are supplymentary
(Basically the cyclic quad thing in the small semicircles)

Question 5

Perpendicular bisector, chord

Answer 5

Perpendicular bisector of chord passes thru the centre of circle
Chord: small semicircle , with bisector, both sides equal

Question 6

Chords equidistant

Answer 6

Chords equidistant from the centre are of equal length

Cords are the small semicircles

Question 7

Tangent and radius

Answer 7

Tangent is perpendicular to radius at point of contact

Question 8

Tangent, external point

Answer 8

Tangents from external points are equal in length

Question 9

1 cm -> mm

Answer 9

10 mm

Question 10

When 5x = ax, a=5

Answer 10

By equating coefficients of x,

Question 11

Use of 3D/ 2D in a graphic

Answer 11

Distorts the graph: vol/area may be interpreted instead of the linear scale

Question 12

Bearing format

Answer 12

7 degrees —> 007

Question 13

Number patterns formula

12,15,18,21

Answer 13

1st v: 12 // incr: 3
Nth term = 12 + 3(n-1)

Question 14

Area of parallelogram

Answer 14

Base x Height (triangles for tgt)

Question 15

Rhombus area

Answer 15

1/2 x diagonal1 x diagonal2

Question 16

Trapezium area

Answer 16

1/2 x height x (parallel side1 length + parallel side2 length)

Question 17

Pyramid volume

Answer 17

(L x B x H) (1/3)

Question 18

Similar volumes

Answer 18

Scale the factor
Vol, 4/7
(4/7)^3 = x/230cm3

Question 19

Sun of int angles of a polygon

Answer 19

(N-2) x 180

Question 20

Visualise a corresponding angle rn

Answer 20

___c/____
/
-c/———

Question 21

D/T graphs : speed increases

Answer 21

:)

Question 22

D/T graphs: speed decreases

Answer 22

:(

Question 23

Probability when choosing 2 at once

Answer 23

N(red)/total x n(red) -1 / total -1