MATHEMATICS |
WISKUNDE |
GRADE 11 |
GRAAD 11 |
MORE EXERCISES |
NOG OEFENINGE |
Special angles : answers |
Spesiale hoeke : antwoorde |
1.1
sin 150° = sin (180° − 30°)
1.2
cos 210° = cos (180° + 30°)
1.3
tan 135° = tan (180° − 45°)
= sin 30°
= − cos 30°
= − tan 45°
1
√3
= ——
= − ——
= − 1
2
2
1.4
sec 150° = sec (180° − 30°)
1.5
cosec 315° = cosec (360°−45°)
1.6
cot 240° = cot (180° + 60°)
= − sec 30°
= − cosec 45°
= cot 60°
2
1
= − ——
= − √2
= ——
√3
√3
1.7
cos 225° = cos (180° + 45°)
1.8
cosec 120° = cosec (180°−60°)
1.9
cot 135° = cot (180° − 45°)
= − cos 45°
= cosec 60°
= − cot 45°
1
2
= − ——
= ——
= − 1
√2
√3
1.10
sin 330° = sin (360° − 30°)
1.11
cos 210° = cos (180° + 30°)
1.12
sec 300° = sec (360° − 60°)
= − sin 30°
= − cos 30°
= sec 60°
1
√3
= − ——
= − ——
= 2
2
2
1
1
1
2
√3
√3
2.1
sin 30° cos 60° cot 45°
= —— x —— x ——
2.2
sec 30° cos 30° tan 60°
= —— x —— x ——
2
2
1
√3
2
1
1
= ——
= √3
4
2.3
4 sin 60° + tan 45° + 2 cot 30°
2.4
sec2 0° + cos2 30° + cosec2 45°
┏
┓2
┏
┓2
┏
┓2
4
√3
1
2
√3
┃
1
┃
┃
√3
┃
┃
√2
┃
= — x —— + —— + — x ——
= ┃───┃
+
┃───┃
+
┃───┃
┃
1
┃
┃
2
┃
┃
1
┃
1
2
1
1
1
┗
┛
┗
┛
┗
┛
3
= 2√3 + 1 + 2√3
= 1 + — + 2
4
= 4√3 + 1
= 3,75
cosec 120° tan 135° sin 150°
cosec (180°−60°) tan (180°−45°) sin (180°−30°)
2.5
——————————————
= ——————————————————————
sec 150°
sec (180° − 30°)
cosec 60° (− tan 45°) sin 30°
= —————————————
− sec 30°
2
1
√3
= —— x 1 x —— x ——
√3
2
2
1
= ——
2
− sin 120° cos 150° + sec2 135° − cos 0°
2.6
———————————————————
sin2 135° cosec 135°
− sin (180° − 60°) cos (180° − 30°) + sec2 (180° − 45°) − cos 0°
= —————————————————————————————
sin2 (180° − 45°) cosec (180° − 45°)
− sin 60° (− cos 30°) + (− sec 45°)2 − cos 0°
= —————————————————————
sin2 45° cosec 45°
√3
√3
3
—— x —— − (√2)2 − 1
—— − 2 − 1
2
2
4
= ———————————— = ————————
(1/√2)2 x √2
1
——
√2
9√2
= − ———
4
cos 240° sin 330° tan 120°
cos (180° + 60°) sin (360° − 30°) tan (180° − 60°)
2.7
——————————————
= ———————————————————————
sin 150° tan 210° cos 120°
sin (180° − 30°) tan (180° + 30°) cos (180° − 60°)
(− cos 60°) (− sin 30°) (− tan 60°)
= ————————————————
sin 30° tan 30° (− cos 60°)
1
1
√3
—— x —— x √3
——
2
2
4
= —————————— = ———
1
1
1
1
—— x —— x ——
———
2
√3
2
4√3
= 3
sin 150° cos 225° sec 10°
sin (180° − 30°) cos (180° + 45°) sec 10°
2.8
—————————————————
= ——————————————————————————
cosec 330° cosec 45° cosec 260°
cosec (360° − 30°) cosec (90° − 45°) cosec (270° − 10°)
sin 30° (− cos 45°) sec 10°
= —————————————————
(− cosec 30°) sec 45° (− sec 10°)
1
1
1
—— x ——
——
2
√2
2√2
= − ——————— = − ———
2 x √2
2√2
1
= − ——
8
sin 150° . cos 210°
sin (180° − 30°) . cos (180° + 30°)
sin 30° . (− cos 30°)
2.9
—————————
= ————————————————
= ———————————
tan 300°
tan (360° − 30°)
(− tan 30°)
1
√3
—— x ——
2
2
√3
√3
= —————— = —— x ——
1
4
1
——
√3
3
= ——
4
sin 210° cos 300° cot 150°
sin (180° + 30°) cos (360° − 60°) cot (180° − 30°)
2.10
——————————————
= ———————————————————————
cos 120° cot 240° sin 330°
cos (180° − 60°) cot (180° + 60°) sin (360° − 30°)
(− sin 30°) cos 60° (− cot 30°)
= ———————————————
(− cos 60°) cot 60° (− sin 30°)
cot 30°
√3
√3
= ———— = —— x ——
cot 60°
1
1
= 3
4
1
1
4
1
1
2.11
— cos2 330° − — sec2 45° − — sin 60°
= — cos2 (360° − 30°) − — sec2 45° − — sin 60°
3
2
3
3
2
3
4
1
1
= — cos2 30° − — sec2 45° − — sin 60°
3
2
3
4
(√3)2
1
1
√3
= — x ——— − — x (√2)2 − — x ——
3
(2)2
2
3
2
√3
= 1 − 1 − ——
6
√3
= − ——
6