Trigonometric Angles Trigonometric angles are very easy to learn if u follow some of these steps- From the table ,just learn the values of sin θ upto 90 and now see that as now move from left to write in sin θ ,the same values will come when you move from right to left in cos θ .Now the next column is of tan θ ,we know that tan θ =sin θ /cos θ ,so we can easy calculate by dividing sin θ and cos θ .Then next we move on to cot θ ,which can be find out by doing inverse of tan θ or by dividing cos θ and sin θ ,as cot θ =1/tan θ or cot θ =cos θ /sin θ .now go to sec θ ,it is reciprocal of cos θ ,cos θ =1/cos θ ,and at the end it is cosec θ ,which can be find out by finding reciprocal of sin's value,as cosec θ =1/sin θ . Angles can be c omplementary angles and complex angles
Respiration in fishes(by gills) Fishes specially bony fishes have internal gills.Gills are protected by external bony plate called operculum.Under the operculum chamber,gill pouches are present which maintains the flown of water in gill pouch and thus gills remain in contact with water.Gills are arranged in row,a comb like structure called gill filaments.Gill filaments are are raised into no. of horizontal flat folds called gill lamellae which are richly supplied with blood capillaries.Here exchange of CO 2 and O 2 takes place by diffusion through blood.
CBSE notes-Light What is the nature, size and position of the image formed of an object at infinity? Explain how it is used as a doctor’s mirror. When an object is placed at infinity from a concave mirror, the image formed is (i) real and inverted (ii) highly diminished and (iii) at the focus When the object is at infinity, the image is formed at the focus of the concave mirror, hence the mirror can concentrate all the parallel rays of the light to its focus. This explains the use of concave mirror as a doctor’s head-mirror. A concave mirror is used as a head-mirror by the doctors to concentrate light on the body parts to be examined.
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